91 trans problem

ged day boys, my 91 gmc sierra 1500 just started giving me trans problems. When i put it in reverse, no swet, i can floor it, when i put it in any other gear, it moves, but at like 10km and the rmp are just getting higher each time i floor it.. so what gives ? oil is good.

troy

Heye dude I know your pain. I have 95 extended sierra I have the same problem except that reverse is the problem area. I am to check my filter as I hear this may be the cause. I drained off a litre of tranny fluid and added Lucas tranny oil in lui of. Same shit. get back to me if you have any luck please. Dickson