Transmission problem

I have a 1994 caprice lt1 with 4l60e trans. The problem I heve with the tranny is it wont shift in to gears (revers or drive) I was driving at 75 mph when it just went in to nutural and it wouldnt run only when acelarate to over 3500 rpm it would shift but it wouldnt go fast the tranny had about 4000 miles after rebuilt I dont think I burnt the tranny one of my friends said it might be the selinoids in the valve body.

Do you hear any kind of whining sound when it does kick in? (sort of like when you zip up a zipper real fast)

no. Before it got messed up the car was vibraiting. I think it has to do with the vibration.

Take it back to the shop that rebuilt it. Something inside broke, possibly the input shaft/drum.

Take it back to the shop that rebuilt it. Something inside broke, possibly the input shaft/drum.

It was rebuilt 2 years ago the car was just sitting on the drive way my warrenty expired long time ago. I was looking for a quick fix and I dont trust the guys who rebuilt the tranny i have had 3 different transmissions from them and they are worth less you cant trust any shop now adays they are looking to still money from people. I dont really want to spend more money on the car it was in a car accident I will be selling the engine and tranny the engine is a LT1