Okay, here is the deal I just bought a 83 k5 and it started acting up. When you start to go its fine untill about 25 then it does not shift to I think is 2nd or 3rd. It is a 700R4, could that be the clutch discs?? Could the rear end have any thing to do with it?? What do I need to look for to determine if the rear end is in need of work or not? I pulled the cover off the rear and I think one of my spider gear lost a tooth. Kinda new at the game, had a little practice on my 75 International Scout and my dad's 70 Travelall. Not chevy I know but love them all!!