OEM parts categories for 1991 Gmc C3500: Body Mounting, Air Conditioning, Audio/Entertainment (A/C & Heater Control Assembly, A/C & Heater Module Assembly, A/C Compressor Assembly, A/C Compressor Mounting, A/C Control System Electrical, A/C Refrigeration System, Air Distribution System/Instrument Panel, Antenna/Fixed, Audio System, Body Mounting & Radiator Mounting, Cluster Assembly/Instrument Panel, Cluster Assembly/Instrument Panel Electromechanical) | Brakes (Brake & Steering System-Hydraulic Lines, Brake Booster/Hydraulic, Brake Booster/Vacuum, Brake Caliper/Front, Brake Caliper/Front & Rear Disc, Brake Lines/Front, Brake Lines/Rear, Brake Master Cylinder, Brake System/Power, Parking Brake System, Parking Brake System/Brake Assembly) | Brakes, Rear Axle, Propeller Shaft, Wheels, Tires (Axle Assembly/Rear, Brake Assembly/Rear Drum, Differential/Locking, Prop Shaft Hanger Bracket, Rear Axle Vent Hose, Road Wheel, Road Wheel/Styled, Wheels & Wheel Covers) | Cab And Body Structure, Mirrors, Doors, Trim, Seat Belts, Wipers (Compartment/Seat Separator, Door Hardware, Door Trim/Side Front, Floor Covering & Sill Plates, Folding Seat Hinge, Front Seat/Bucket, Instrument Panel & Related Parts, Lamp/Dome, Lamps/Cargo, Mirror/Outside Rear View, Rear Seat/Folding, Seat Belts/Bench Seat, Seat Belts/Bucket Seat, Seat/Bench, Seat/Bucket, Seat/Split, Sheet Metal/Body, Trim Interior, Trim/Interior-Roof, Windshield & Windows, Wiper System/Windshield) | Cooling System, Grille, Oil System (Engine Block Heater & Related Parts, Engine Coolant Fan & Clutch, Engine Coolant Fan-Auxiliary, Engine Oil Cooler And Lines, Engine Oil Filter Adapter, Engine Oil Pressure & Temperature Switches, Grille/Radiator, Grille/Radiator Lower, Hoses & Pipes/Radiator, Pulleys & Belts/Accessory Drive, Radiator Assembly, Radiator Mounting & Related Parts) | Engine (Clutch Assembly/Diaphragm Spring Type, Clutch Cylinders/Hydraulic, Clutch Linkage, Engine & Transmission Mounting, Engine Assembly & Partial Engine) | Frames, Springs, Shocks, Bumpers, Fascias (Bumper/Front, Bumper/Rear, Frame, Spare Wheel Carrier, Springs/Front & Rear, Springs/Rear, Suspension/Rear, Trailer Hitch Platform) | Front Axle, Front Suspension, Steering (Axle Assembly/Front, Coolers/Power Steering, Steering Column/Non-Tilt, Steering Column/Tilt, Steering Gear Assembly, Steering Linkage, Steering Pump Assembly, Steering Pump Lines, Steering Pump Mounting, Steering Shaft & Coupling/Intermediate, Steering System & Related Parts, Suspension/Front) | Front End Sheet Metal, Heater (Heater & Blower Assembly, Heater & Vent Control Cables & Harness, Heater Control Assembly, Hoses & Pipes/Heater & Related Parts, Insulation & Seal/Hood, Jack & Tool Stowage, Labels, Lamps/Under Hood, Sheet Metal/Front End) | Fuel System, Exhaust, Emission System (A.I.R. Pump & Related Parts, Accelerator Control, Accelerator Control Engine Compartment, Accelerator Control Pedal & Rod, Air Intake System, Cruise Control, E.C.M. Module & Wiring Harness, E.G.R. & Exhaust Pressure Regulator Valves, E.G.R. Valve & Vent Tubes, Exhaust System, Fuel Filter, Fuel Supply System-Front, Fuel Supply System-Rear, Fuel Tank And Mounting, Injection Pump/Fuel, M.A.P. & Oxygen Sensors & E.S.C. Module, Throttle Body Injection, Vapor Canister & Related Parts) | Maintenance Parts, Fluids, Capacities, Electrical Connectors (Normal Maintenance Replacement Parts) | Rear Body Structure, Moldings & Trim, Cargo Stowage (Bedliner/Pickup Box, Decals & Nameplates/Endgate, Decals/Pickup Box Side, Fender/Pickup Box, Moldings/Cab & Body Side, Pickup Box/Fleetside, Pickup Box/Stepside, Stripes/Body Side & Endgate) | Starter, Generator, Ignition, Electrical, Lamps (Auxiliary Battery & Wiring, Battery Cables, Distributor/Ignition, Generator Mounting, Horn Button & Contact, Lamps/Fog, Lamps/Front, Lamps/Rear, Lamps/Roof, Spark Plug Wiring, Starter Motor, Starter Motor And Mounting, Wiring Harness/Chassis, Wiring Harness/Engine, Wiring Harness/Instrument Panel, Wiring Harness/Rear Lamps, Wiring Harness/Trailer & Camper Wiring Harness) | Transmission - Automatic (Automatic Transmission Assembly, Automatic Transmission Auxiliary Accumulator Valve, Automatic Transmission Case & Related Parts, Automatic Transmission Clutch Gears, Automatic Transmission Control Valve, Automatic Transmission Oil Pump, Automatic Transmission Overrun Clutch, Automatic Transmission Parking Lock Linkage, Automatic Transmission Valve Body, Shift Control, T.C.M. Module & Wiring Harness, Throttle Valve Cable, Transmission Filler Tube & Oil Cooler Pipes) | Transmission - Manual (Manual Transmission, Shift Control)