Here is a step by step with pics
http://www.customclassictrucks.com/t...all/index.html
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Painless 10206 wiring harness for 1967-1972 Chevrolet and GMC pickup trucks. Factory style bulkhead connectors and additional GM connectors makes this harness a custom fit. Nothing could make your vintage Chevrolet truck easier to re-wire.
18-CIRCUIT WIRING HARNESS INCLUDES:
Accessory plug.
Backup lights/cruise control.
Air conditioning and heat.
Ignition and starting.
Horn
Emergency flashers.
Dash instruments.
Headlights, taillights, brake lights, turn signals
Radio
Constant and ignition hot
Wipers
Dome light.
Charging
EXTRA CIRCUITS INCLUDED FOR:
Electric choke for carburetors.
Electric engine cooling fan.
Electric fuel pump.
Power antenna.
Power windows.
Power door locks
Third brake light.
Keep in mind that this wiring harness includes more circuits than the stock vehicle. This is so that you may add the extra items listed easily should you choose to do so. If you do not need the extra items, just delete them from the harness when installing.