i own a 1983 chevy silverado pickup with a 700r4 auto transmission in it. i was on my way home from the mountains when i ran into some problems. i was going up a pretty steep incline when the transmission just slipped out of gear and just started revving. i think i was in 3rd. so i stopped on the side of the highway and figured it might just be a one time thing... so i drive off. it shifts HARD into second then when it tries to shift into third it just revs... i pulled over and thought maybe i needed some tranny fluid but it wasnt that low... maybe a quart... which isnt too much... i think i got a major problem here... but any help would be appreciated. the thing is that i just put this transmission in about a year and a half ago... it doesnt have but 20,000 miles on it since its been rebuilt... any help or insight you could give would be greatly appreciated. feel free to ask questions and ill do my best to give an answer.
Without question the third gear clutch pack is gone. What the rebuilder no doubt failed to do is replace the steels with thicker aftermarket ones which don't warp as the factory ones tend to do also it tightens up the clearances too. Also the 700s suffer from low line pressure and a correction package cures this by replacing the weak stock spring that's located in the front pump. Don't give up on this unit it's a good transmission it just needs proper building and upgrades.