I believe 81-86 trucks were the ones with non-computer controlled electric choke Quadrajets. Here's what mine looks like in this other thread where we were talking about chokes.
http://67-72chevytrucks.com/vboard/s....php?p=7825067
I have mine connected to key-on 12V from the fuse box with 18 gauge wire. I think anything from 18 gauge to 12 gauge would be fine, although 12 gauge would probably be overkill.