OK notjenny, please excuse the delay, had a situation. We need model, engine, transmission. VIN, and RPO codes.
My 1990 FSM has 6 different 4L60 internal wiring configuartions. Wow. So. IDK if even FRSCKE1 can find it without the information below, but do I know he's got the books for 1992. LOL.
IDK if the Chevy books we have will accurately cross refererence either. They say Chevrolet Truck, both FSM, and Electrical manual. My 1985-91 Parts book, says G Van.
GM is usually pretty good about parts interchangability. The Transmissions specific ID codes may be the same as GMC, IDK.
What Engine/Tranny combo? I'd assume 350/4L60 but it apparently matters, and I can't be specific in the wire color ID without the year specific GMC Vandura FSM manual. So. VIN, any RPO code regarding engine and transmission will help ID your specific model transmission.
I used to have my parts guy at the Dodge dealer look up stuff on his computer, all the time. I'd definitely try that at Chevy if I had to. I can try that not trunning troubleshooting anway, and report back. Stay with it. And again, Welcome.
Good Hunting.