[1971Stepside]

First off let me begin with the fact that I am no transmission specialist. I will just pass along what I have learned along the way. My brother had to replace the engine in his truck so while he was at it he decided to change the oil and filter in his transmission. He wanted everything to be fresh. Anyway, the transmission began doing things like you are experiencing. It then began slipping and getting worse and worse on his drive from Texas to Missouri.

We took the truck to a trans shop in town and the first question the guy asked us was if we had recently changed the fluid. When we told him that we had he said we shouldn't have!! He said that unless your transmission fluid is changed on a normal basis you shouldn't mess with it. The fluid gets small particles in it from the clutches and if removed the new fluid is too slick to get the clutches to work properly. He said you are best to leave the old oil in and just make sure it is not leaking and topped off. $1000 later we were rolling again. This was a 4L80E transmission in a 94 Chevy 4x4.

I will bet by changing the fluid you have exposed worn plates in your tranny. It isn't good news for you, but at least a 350 is only about $300 to have rebuilt. That 4L80E was very expensive!!