Chevy to GMC headlight harness questions, upgrades

[bambbrose]

Good day everyone.

I have a 72 GMC (technically a Jimmy) that was "rebuilt" sometime in the past out of a Jimmy body and a blazer front end.

I'm putting it back to a Jimmy 4 headlight front end at the moment.

I'm posting here as I'll get more feedback and my question is applicable to the trucks the the blazer/jimmy crowd.


I have a standard 72 blazer headlight harness currently (w/ gauges). I have the original external regulator alternator with the regulator on the radiator support.

I was just about to pull the trigger on a new GMC headlight harness, but I got a quote of 8 weeks lead time as they are out of stock and needing to build new ones. That won't work for me.

That got me digging into the factory service manuals to see the difference. Unfortunately I cannot find a GMC specific wiring diagram, but I did find the Chevrolet diagram, as well as the GMC parts diagram. It would appear that the only actual difference is that a high beam is run off onto a new plug for the GMC.

I'm considering saving the $200 and just rebuilding my harness. Can anybody confirm that I just need to move the high beam wire to a new one of these plugs (attached pic), which I can pick up on ebay for about $6 each?


Can someone please confirm if the outer lamp on the GMC is just a low beam, and the inner is a high beam? Or is the outer a lo/high beam, and the inner just a high beam?



And my final question, is there any reason to upgrade the wiring gauge or similar while I'm in the harness for better light output? What is the limiting factor? I'm sticking with OEM type lamp assemblies, but if there is a way to make them "like new" or better while I'm at it I figured I'd check.


Thanks!