Rear lights/wiring and shifting seqence

The wiring info I found for this model year, says GMC, tail lamps. The wire colors are voltage.

Usually on the side of the tranny, forward all the way is park, next detent is reverse, next is neutral drive--drive 2--drive 1. I'm trying to do this from memory, I will double check if possible. If your under the vehicle working the shift linkage by hand, there safety issues. Make sure you have helper inside with their foot on the brake, incase my memory isn't that great, you don't want the vehicle taking off and running over you or somebody else, when you thought it was in park.

Safety is your responsibility.

My info for your model year isn't great.

That shift pattern a/t I gave you should be universal for GM. Operatiing the shift linkage on side of tranny by hand, maybe this more clear, all the way clockwise should be park, One detent ccw is reverse, next detent ccw is neutral, Hopefully I got d--d2 and d1 correct.

Any shifting, be safe.