Mastering GTO Restorations: Electrical Guide - ENGINE Apr 17, 2015Painless offers exceptional reproduction wiring harnesses. Its universal GM muscle car kit fits all GM A-, F-, and X-Body cars from 1964 to 1974 and an optional engine compartment harness can also be included. It is a more generic version of what was offered in the cars originally and uses standard GM plugs, fittings, and color coding. Painless Wiring While the factory wiring harness wasn't completed hacked in their '67 GTO, Rich at Deboss Garage went ahead and rewired the Pontiac for ease of mind. With a build of this caliber, the last thing you want to do is chase down wiring gremlins! Watch him show you how to lay out our 25 circuit Pro-Series harness and fit it to the car!