1415 Radford Road
Christiansburg Va. 24073

Main Ph: (540) 382-3972
Toll Free: (855) 263-6400
Sales fax: (540) 382-9169
Main fax: (540) 382-4696

Automotive Recycling Association (ARA) Used Part Guide

Brake System Exhaust System Lamps Seats
Bumper Fender Movable Glass Steering
Cooling System Front End Assembly Quarter Panel Structural Parts
Door Fuel System Rear Body Panel Suspension
Electrical Accessories Heating and A/C System Rear Closure Panel Trim Hardware
Engine Drive Train Hood Restraint System Wheel
Instrument Panel Roof Panel

ARA Interchange Committee Notes

Developed at the ARA Standard Guide to Used Parts - February 16, 2000

This standard is intended to promote commerce in used automotive parts and as a guide for interchange development. The Automotive Recycling Association's goal is to create a unified description of used parts, thereby promoting all forms of commerce in automotive recycling. This standard is designed for use across all electronic platforms and computer systems.

To reach this goal all parties selling, buying and installing used parts need the common language represented by this standard. Those developing products, services, interchange or evaluations containing used parts are encouraged to use the standard. The ARA has created this standard as an inclusive, cooperative effort between everyone interested in used automotive parts, interchange standards, and recycling.

For each used part assembly, this document gives a complete description of what is included with the assembly as delivered for reuse. In addition, there is a description of what is not included, but may be additionally available depending on how the source vehicle was optioned. There are comments and footnotes to clarify the reasons why the used part assembly is prepared for reuse in the way described.

Brake System

Assembly Included Components Not Included, But May Be Available Comments
Front Hub and Rotor All variations of Front Brakes as removed including Rotors and Hub if attached to Rotor Vehicles may not have Hub included if easily detached from assembly N/A
Rear Hub and Rotor All variations of Rear Brakes as removed including Drum and Rotor Vehicles may not have Hub included if easily detached from assembly N/A
Hub See Suspension N/A N/A
Front Or Rear Disc Caliper Complete up to Hose ABS Sensor, Mounting Bracket or Support and Emergency Brake Cable N/A
Master Cylinder Master Cylinder Reservoir, Cap and Integrated Sensor ABS System Brake Lines as detached from Master Cylinder N/A
Antilock Brake Assembly Accumulator, Modulator and Pump ABS Computer Mounting Bracket and Brake Lines N/A
Accumulator Accumulator, not integrated with Modulator and Pump Mounting Brackets N/A
Modulator Modulator, not integrated with Accumulator and Pump Mounting Brackets N/A
Pump Motor Pump Motor, not integrated with Accumulator and Modulator Mounting Brackets N/A
Antilock Brake Electronic Control Module Wires to the first disconnect N/A N/A
ICAR UPCR Codes: BR11, BR51, BR71

Bumper

Assembly Included Components Not Included,But May Be Available Comments
Steel Bumper Front Or Rear Guards, Pads, Unbolt Reinforcement, Energy Absorbers, Mounting Brackets, Lamps (if Bumper Mounted), End Caps, Step Plates, Fillers (if Bumper Mounted) Valance Panel or Air Dam are not included unless they are an integrated part of the Bumper Assembly Be aware of extra options such as fog lamps and extra brackets or trailer hitches.
Rubber Fascia Cover, Absorber Pad, Unbolt Reinforcement, Lamps (if Fascia Mounted), End Caps, Fillers and Retainers if Fascia Mounted Valance Panel or Air Dam are not included unless they are an integrated part of the Bumper Assembly Fascia mounted lamp options can change the shape of the entire part. Check for these before ordering.
ICAR UPCR Codes: BU01S, BU02P, BU11S/P, BU21, BU22

Cooling System

Assembly Included Components Not Included, But May Be Available Comments
Water Pump Water Pump Pulleys and Brackets N/A
Radiator Core, Tanks, Internal Oil Coolers and permanently affixed fixtures Shrouds, Cooling Motors, Hoses, Fittings, Electrical Sensors, Switches, Pressure Cap, Cooling Lines and Fan Blades Some attached Sensors and Switches may be included but may not be required
Electric Cooling Assembly Motor, Shroud, Integral Mounting Brackets, Fan Blade up to first disconnect N/A The entire assembly is sold complete as removed from the radiator support.
Fan Blade Integral Clutch Removable Clutch N/A
Removable Fan Clutch Fan Clutch Fan Blade N/A
Fan Shroud Shroud N/A N/A
Cooling Motor Motor and Wire to first disconnect Fan Blade, Shroud, Mounting Bracket N/A
ICAR UPCR Codes:CO01, CO11, CO21, CO22

Door

Assembly Included Components Not Included,But May Be Available Comments
Door Left or Right, Front or Rear, Sliding, Cargo and Back Door Glass, as optioned,1 door-mounted weather-strips, regulator motor (if power), lock hardware (if power), outside handle, half of hinges if welded to door. Moulding1, pillar-welded hinges, pillar-mounted weather-strips, lock cylinder, interior trim panel, pillar-mounted latch, mirror, wiring harness and in door safety restraints (seat belts). Not enough is known about mirrors to permit the part to be properly included.2 Safety restraints (seat belts) in the door are not included because they are part of the interior trim, with color and option variations.3

See attached inventory description standard for option description codes.

See attached damage location standard for locating damage.
ICAR UPCR Codes:DO01, DO21, DO22, DO31S/A/P

Electrical Accessories

Assembly Included Components Not Included,But May Be Available Comments
Battery Battery Cables Fuesable links, if present, are part of the cables.
Starter Starter Integral Solenoid Non Integral Solenoid, Heat Shield N/A
ECM (Electronic Control Module) ECM Unit and Wire to first disconnect ECM Prom In most cases the Prom should be exchanged with the one in the removed unit. Follow repair recommendations from the manufacture.
 

Engine Drive Train

Assembly Included Components Not Included,But May Be Available Comments
Engine Assembly Complete Engine as removed from the vehicle including Cylinder Heads as optioned Alternator-Pulley-Regulator, Alternator Wiring Harness, Power Steering Pump, Power Steering Hoses, Power Steering Reservoirs, Power Steering Pulley, Starter-Solenoid, Engine Mounts, Engine Mounted Igniter and Fuel System Engines may require exchange of manifolds, fuel systems, or oil pans to be installed.
Engine and Transmission Mounts Complete Unbolted Unit Welded or Bolted on Frame or Body Brackets Engine Frame is a separate part.
Automatic Transmission Converter, Electrical up to first disconnect Linkage and Cables External computers may be included in some cases.
Manual Transmission Electrical up to first disconnect Shift Levers, Cables, Removable Clutch Housing, Clutch Slave Cylinder N/A
Transfer Case Complete with Internal Electronics up to first disconnect Divider Housing (Transfer Case Adapter) and Externally Mounted Electronic Components (Shift Motor) Pinion flange may not match - change as needed.
Driveshaft, front or rear Complete to Axle and includes CV-Joint, U-Joint and Slip Yoke Pinion flanges are part of the axle assembly and not the drive line. N/A
Front Or Rear Integral Differential Housing to Backing Plates or Knuckles, Axles, Internal Gears, Electronic Control Units to first disconnect and Pinion Flange Removable Axles and External Electrical Control Units, Drums, Disks, Brake Hardware, Control Arms, Track Arms and Sway Bars Gear ratios will differ and will need to be matched. Companion Flange may not match - change as needed. Specify if locking is required. Front or Rear Integral Differential does not have drop out Carrier Assembly. Gears must be removed separately.
Carrier Assembly Complete Gear Set and Case with Non-removable Stub Axles and Flanges Removable Axles and External Electrical Control Units, Drums Disks, Brake Hardware, Control Arms, Track Arms and Sway Bars Gear ratios will differ and will need to be matched. Specify if locking is required. Companion Flange may not match - change as needed.
Front Or Rear Integral Differential, Independent Suspension Housing, Non-removable Axles, Internal Gears, Electronic Control Units to first disconnect and Pinion Flange Removable Axles and External Electrical Control Units, Drums, Disks, Brake Hardware, Control Arms, Track Arms and Sway Bars Gear ratios will differ and will need to be matched. Specify if locking is required. Companion Flange may not match - change as needed.
 

Exhaust System

Assembly Included Components Not Included,But May Be Available Comments
Exhaust Manifold Exhaust Manifold Tailpipe, Muffler, Header Pipe and Oxygen Sensors Catalytic Converters are typically not sold used because of Federal Clean Air Regulations, preventing reuse of untested units.
Header Pipe Pipe, flanges, and connectors including Oxygen sensor, electrical up to first disconnect. Header pipes go between the exhaust manifold and the catalytic converter, and are after any turbo charger. N/A
ICAR UPCR Codes:EX01, EX11

Fender

Assembly Included Components Not Included, But May Be Available Comments
Full Frame:Fender Left Or Right Full Frame: Bolted on Inner Panel and Inner Skirt, Lamps attached on the side and Fender Mounted Splash Shields. Full Frame: Moldings, Extensions which are part of Header or Headlight and Antenna. Extensions that are part of the Header and Headlight Assembly are not included with the Fender. Not enough information about Antennas is known to automatically select the correct part.
Unitized Frame:Fender Left Or Right Unitized Frame: Lamps attached on the sides, Unboltable Inside Skirts, Extensions and Fender Mounted Splash Shields. Unitized Frame: Inner Sheet Metal, Moldings, Extensions which are part of Header or Headlight and Antenna. N/A
Antenna Complete antenna assembly. N/A May be power or manual.
ICAR UPCR Codes:FR01S/A, FR11S/A, FR21P

Front End Assembly

Assembly Included Components Not Included,But May Be Available Comments
Front Section Full Frame Vehicle: Front Bumper Assembly (see front bumper), Fender Left and right (see fender), Hood (see hood), Header Panel (see header panel), Grille (see grille), Valance Panel, Bolt-on Radiator Support, Radiator, Condenser and Attaching Filters. Frame Rails, Frame Horns, Sub-frame, Cross-members, Suspension Components, Molding1, Ornaments, Bolted-on Parts on Inner Structure, Antenna and Equipment bolted to the Inner Fender Skirts, including the Engine Cooling Fan Assembly Moldings are not included because there is not enough information about the part to automatically select the correct one1. Antennas are not included for the same reason
Full Cut4 Unitized Frame Vehicle: Including Cowl: All Inner Sheet Metal including Aprons/Rail beyond factory joints. N/A N/A
Partial Cut4 Excluding Cowl: Cut anywhere ahead of Firewall Unitized Frame parts do not include rear portion of Frame Components See ARA Standard Cut Lines Guide chart #1.
Header Panel Grille, Lamps, Lamp Doors (if Header Mounted) and Mounting Brackets. Molding (Emblem and Ornament) N/A
Grille Attaching Brackets, Lamps/Fillers (if Grille Mounted) Molding (Emblem and Ornament) N/A
ICAR UPCR Codes:FE01S

Fuel System

Assembly Included Components Not Included,But May Be Available Comments
Fuel Tank Fuel Tank Fuel Lines, Tank Mounted Pump. Non-integral Filler Neck, Sending Unit and Mounting Straps N/A
Fuel Pump Fuel Pump, Integral Sending Unit to first electrical disconnect N/A N/A
Lines Lines to first disconnect N/A N/A
Sending Unit Non-integral with Pump N/A N/A
Tank Switch Valve Valve and wiring up to first disconnect. Switch and wires. Complete second fuel tank add on kits are available.
ICAR UPCR Codes: FU01, FU02, FU03, FU11, FU21

Heating and A/C System

Assembly Included Components Not Included,But May Be Available Comments
A/C Condenser Core and Brackets permanently affixed to the Condenser Electrical Sensors, Switches, Valves, Dryers, Filters, Shrouds, and Cooling Motors Note: Flush Condenser and change Dryer when servicing Refrigerant
Heater, Vent, Air-Conditioning Housing (HVAC) Housing Assembly and Integrated Sensors and Wires Blower Motor, Heater Core, Evaporator Core, and Removable Electrical Components N/A
Blower Motor Blower Motor and Fan to first electrical disconnect Case Assembly and Power Leads N/A
Heater Core Heater Core Pipes, Hoses, Clamps and Cover N/A
Evaporator Core Evaporator Core Pipes, Hoses, Clamps, Dryer and Filter A/C Dryer is a service part and is not sold used
ICAR UPCR Codes: AC01

Hood

Assembly Included Components Not Included, But May Be Available Comments
Hood Panel Insulator as optioned, Latches, Catches, Hinges if attached to Hood on removal Prop, Header or Core Support Mounted Latches and Catches, Moldings, Emblems and Ornaments Emblems and Ornaments may be available, but there is not enough information about the part available to automatically select the correct one
Hood Latch Safety catch, and mounting bracket. Release cable. N/A
ICAR UPCR Codes:HO01, HO11, HO21S/A/P

Instrument Panel

Assembly Included Components Not Included,But May Be Available Comments
Dash Assembly Complete removed Dash Assembly including all Vents, Switches and Face Plates not attached to the Sound System Not included are the Radio Face Plate, Climate Control and any vehicle attached duct work, the Instrument Cluster, Air Bag Assembly, Dash Pad, Wiring Loom and Switches as they detach from the vehicle at their first disconnects. Radio Face Plate may or may not be part of the Radio depending on construction. Dash Wiring Loom is a separate part
Instrument Cluster Complete instrument cluster assembly including printed circuit board and lighting up to first disconnect. Dash pad, speedometer cable, wiring harness, and dash assembly. N/A
ICAR UPCR Codes:IP01, IP11

Lamps

Assembly Included Components Not Included, But May Be Available Comments
Headlight:Composite Housing, Bezel, Lens and Trim Bumper Filler, Fender Extensions, Non Integrated Wire Harness, Printed Circuits and Headlight Bulb. Wire Harness and Snap Out Printed Circuits are sold as a separate part
Headlight:Capsule Type Housing (when serviced separately), Headlight Bulb, Bucket and Ring, Bezel, Park-light or Sidelight when contained within Bezel. N/A N/A
Headlight Mounting Panel Headlight Adjustment Mechanism Brackets, Headlight Assembly, Park-lights and Grille N/A
ICAR UPCR Codes:LA01, LA11, LA21, LA22, LA23, LA31, LA32

Movable Glass

Assembly Included Components Not Included,But May Be Available Comments
Glass:Door Trim (as supplied by OEM), Wires to first disconnect, Riveted Parts and Adhesively Attached Parts. Handles, Hinges, Mirrors, Deflectors, Window Regulators and any Bolted-on parts Rivets may need to be removed and replaced to facilitate installation
Glass:Quarter Trim (as supplied by OEM), Wires to first disconnect, Riveted Parts and Adhesively Attached Parts. Handles, Hinges, Deflectors, Window Regulators and any Bolted-on parts Rivets may need to be removed and replaced to facilitate installation
ICAR UPCR Codes:MG01, MG11, MG21, MG31, MG32, MG41, MG51

Quarter Panel

Assembly Included Components Not Included,But May Be Available Comments
Quarter Panel (Section) Left Or Right All Inner Sheet Metal, Extensions, Fuel Door as optioned, Lock Pillar, Mud Guards or Fillers if attached and attached Side Lamps. Moldings, Interior Trim, Safety Restraints, Fuel Tank or Neck and any Rear Facing Lamps. Rear Facing Lamps are a separate part. See ARA Standard Cut Lines Guide.
Quarter Trim Left or Right Trim, clips, and end caps. Glue on trim or decals. Trim is identified by part numbers.
ICAR UPCR Codes:QT01S/A/P, QT11S/A

Rear Body Panel

Assembly Included Components Not Included,But May Be Available Comments
Short Rear Body Assembly Both Quarters, Rear Body Panel, Inner Structure, Trunk Lid, Lamps, Reflectors and Bumper. In Uni-Body Vehicles the Rail Structures are included. Fuel Tank, Roof Rack, Spare Tire Carrier, Rear Suspension, Antenna, Glass, Seats, Interior Trim, Safety Restraints, Moldings, Spoilers, Luggage Racks1 and Full Frame Car Frame Section. In Full Frame Vehicles the Frame Rails are not included.
Long Rear Body Assembly And Roof Both Quarters, Roof, Rear Body Panel, Inner Structure through the floor, Truck Lid, Lamps, Trunk Lid, Reflectors, Bumper and Glass (as optioned1) Fuel Tank, Roof Rack, Spare Tire Carrier, Rear Suspension, Antenna, Seats, Interior Trim, Safety Restraints, Moldings and Spoilers.1 In Full Framed Vehicles the Frame Rails are not included. Glass as optioned means that all Glass is delivered as Source Vehicle was built and Glass type must be verified to get correct delivery.1
ICAR UPCR Codes:RB01S/A

Rear Closure Panel

Assembly Included Components Not Included,But May Be Available Comments
Deck Lid & Tailgate Lid-Mounted weather-strips, Lid-Mounted Latches, Locks, Half of Hinges if welded to Lid, Lamps or Reflectors is Lid Mounted, Defogger (if Optioned), Wiper or Wiper Motor (if optioned), Glass as optioned1, Defogger (if optioned), Wiper/Wiper Motor (if optioned), Glass weather-strip, Gate-Mounted weather-strips, Gate-Mounted Latches, Locks, Gate-Mounted Lamps or Reflectors, or Exterior Trim Panels, License Bracket and half of Hinges if Bolted-on Mouldings1, Fillers, Lock Cylinder, Interior Trim Panels, Rear Body Panel-Mounted Latches/Locks, Wiring Harness, Spoilers, Luggage Racks and Spare Tire Carrier Spare Tire Carriers are a separate part4. Variations in body option codes do not permit the correct Spoilers and Luggage Racks to be supplied3
ICAR UPCR Codes:RC01SA/P, RC11S/A/P, RC21S/A/P, RC31S/A/P

Restraint System

Assembly Included Components Not Included,But May Be Available Comments
Seat Belt (Motorized Assembly) Belt, Retractor Unit, Motor up to first electrical disconnect and Track Assembly N/A Color as optioned
Airbag Airbag Module, Cover as optioned Cover Non-Integrated, Clock Spring Sensor, Computer, Color as needed Color as optioned
Tensioners - Active Unit N/A N/A N/A
Integrated Rear Safety Seat N/A N/A Since it is an integrated part of the Rear Bench Seat, the Bench Seat must be purchased for this option
Seat Belt (Non-Motorized) Seat Belt and Retractor Unit N/A Color as optioned
ICAR UPCR Codes:RE01, RE11, RE21, RE22, RE31, RE32, RE41, RE51

Roof Panel

Assembly Included Components Not Included,But May Be Available Comments
Roof Sunroof Panel or Glass as optioned with weather-strips, Motor, Roof Rails and Roof Panel Track Mechanism. Sunroof Exterior Metal Panel or Glass Drip or Scalp Moundings1, Headliner, Safety Restraints, Back Glass, Windshield, T-Top, Vinyl Covering and Luggage Rack T-Tops are separate parts.4 Not enough information about Vinyl Roof Covering options is known to supply the correct part.2
ICAR UPCR Codes:RO01S/A, RO02S/A, RO11

Seats

Assembly Included Components Not Included,But May Be Available Comments
Seat Seat and Track if integral, Integrated Power Track, Motor and Controls if on Seat. Seat Belts and Retractors made into Seat. Seat Track if removable, Controls if not part of Seat, Seat Belts if not part of Seat. N/A
Track Integrated Motor, Transmission Cables, Electrical Wiring up to first disconnect. Seat and Controls that are not part of Track Assembly. N/A
ICAR UPCR Codes:SE01, SE11

Steering

Assembly Included Components Not Included, But May Be Available Comments
Steering Gear Steering Gear Pitman Arm, Coupler, Intermediate Shaft and Mounting Brackets N/A
Long Rack & Pinion Tie Rods and Ends Assemblies with Integral Electrical Controls up to first disconnect Coupler and Mounting Brackets N/A
Short Rack & Pinion With Integral Electrical Controls up to first disconnect Tie Rods, Tie Rod Ends, Couplers and Mounting Brackets N/A
Power Steering Pump Pump, Reservoir if integral to Pump Bracket, Pulley or Reservoir Remote for Pump N/A
Knuckle/Spindle Complete with Hubs as required N/A If Knuckle/Spindle is part of Strut Assembly, it will fall under Strut Category
Steering Column Column, Levers, Internal Wiring and Switches. Steering Columns are delivered as the Column is detached from the first disconnect to the Steering Gear, Cowl and Dash Airbag Assembly is not included. Additional Wiring and Trim around the Dash Assembly. Ignition Key and Lock Cylinder may be included, but will need to be re-keyed. Steering Wheel may be included, but varies as optioned Column Wire Loom is included as optioned for Wipers, Lights, Radio and Speed Control
Hub See Suspension N/A N/A
ICAR UPCR Codes:SR01, SR11, SR21, SR41, SR51

Structural Parts

Assembly Included Components Not Included,But May Be Available Comments
Complete Bare Frame Bare Frame Bolted-on Components and Cross-members, Engine Mounts, Transmission Mounts N/A
Bolted Radiator Core Support Radiator Core Support N/A N/A
Welded Radiator Core Support Upper & Lower Tie Bars and Side Panels Partial upper & lower Unibody Side Rails & Aprons for Welded Units N/A
Side Rail Assembly Rail, (upper), Front Strut Tower & Apron, Rail (front lower) Upper Wheel House Extension, Radiator Support, Front Panel, Battery Tray, Lower Reinforcement, Support Assembly, Apron Assembly N/A
Rocker Panel Complete Assembly Pillar Assemblies with Molding and Retainer, Rocker Panels, Pillars See ARA Standard Cut Lines Guide - order as needed
"A"-Pillar Front Door Hinge Pillar including partial W/S Pillar, Cowl, Rocker, Welded on Door Hinge Exact dimensions are as required See ARA Standard Cut Lines Guide - order as needed
"B"-Pillar Center Pillar Assembly to Roof Partial Rocker Panel and Floor Panel as needed Roof Panel, Rockers and Floor Panel See ARA Standard Cut Lines Guide - order as needed
"C" "D" Pillar - See Quarter Panel N/A N/A N/A
Removable Sub-Frame (Engine Cross-member) Removable Sub-Frame or Engine Cross-member for the Engine Sway Bars, Torsion Bars, Suspension and Engine Mounts Sway Bars are included only as optioned
Cross-member (Removable) Cross-member (removable) Bolted-on Brackets and Mounts N/A
ICAR UPCR Codes:SP01S/A, SP05S/A, SP06S/A, SP08S/A, SP11S/A, SP21S/A, SP22S, SP31S/A, SP41S/A, 51S/A, SP71S/A, SP91S/A

Suspension

Assembly Included Components Not Included, But May Be Available Comments
Strut (Front & Rear) Spring and Mounting Plate with Integral Bushings or Spindle Steering Spindle and Knuckle See Steering
Coil Spring Coil Spring N/A N/A
Leaf Springs Leaf Spring and Bushings Shackle, Frame Mounting Bracket, Spring Bolts, and U-Bolts N/A
Trailing Axle Axle Spindle to Spindle, Control Arms, Track Bars Drums, Discs, Brake Hardware, Attached Cables, Hydraulic Lines and Sway Bars Sway Bars are included only as optioned
Hub Hub, as removed from brake and knuckle assembly Lug Bolts, Knuckle Bearing, and related Brake Components Some Hubs separate from Brakes - these do not include Brake Parts. Others do not and in this case the Brakes are included.
ICAR UPCR Codes:SU01, SU11, SU21, SU31, SU41, SU51

Trim Hardware

Assembly Included Components Not Included, But May Be Available Comments
Exterior Mirror Housing, attached hardware, Manual Controls and Cable Wiring to first disconnect. Wiring past first disconnect, Mirror Control if removable, Bolts and Gasket. Mirrors have many options, and must be ordered accordingly.
ICAR UPCR Codes:TH41

Wheel

Assembly Included Components Not Included,But May Be Available Comments
Wheel Wheel Trim Ring and Cap Styled Wheels as optioned
Tire Tire Wheel, Hubcap, Wheel Cover N/A
ICAR UPCR Codes:WH01S/A

Footnotes

1. As optioned means the part will be delivered with the options of the source vehicle. If the vehicle on which the part is to be installed has different options, these changes are the responsibility of the party having the work done.

2. On many part types the proper options installed on a particular vehicle may not be easy to determine. Manufactures routinely install parts which have significant variations without making a record of the change. In the case of mouldings variations with in single production run is not uncommon. Auto Recyclers may be able to closely match what is needed. In order for a Recycler to supply this service a detailed description of what is required must be supplied. The Recycler can only guarantee that the major assemblies will fit and work without this additional information.

3. Automatic selection of many optional parts is not possible with the limited information currently supplied by the automated systems. Work is underway to increase the flexibility of the systems now in use. Until there are improvements, those that are having the work done must be responsible for making additional information available to the Automobile Recycler.

4. Some parts, although they are attached to the part in question are sold as separate items. There are several conditions which cause this to be true. Some parts have too high of a demand as a separate item, which if included would raise the cost of the primary part above that established in the market. Other parts, if sold with the primary part will adversely affect the value of yet another item. Finally, some parts have so many options involved in their manufacture that including them on the primary part reduces that part's utility.