Have a 94 z, 3500 converter 4.10 gears some weight reduction. Rebuilt the trans after it broke the sprag from the first rebuild. Seems like 3rd gear sometimes goes in right but sometimes you have to let off it then hit it again. It will hit the limiter if you dont. I had the same problem with the stock converter as well before the sprag broke. It was fine the first rebuild then seemed like it started not going in 3rd right. Now 2nd is going out as well, I think the cluthes are burnt up on that though as I have to wind first up then hit it to 3rd or it will just slip. 3rd acts up only on hard acceleration. Converter is a Vigilante (precision), a B&M shift kit and a TCI rebuild kit. My dad rebuilt the trans the first and second time, he is no stranger to transmissions. We have an 8 second drag radial car with a 'glide and he is experienced in the 400,350, 'glide and others. He also did some 700r4s which are similar. We just need to know what direction to go in. I guess I gotta start spending some money lol.

 

i'll be interested to see what people say, I had my trans built 1k ago and the spag broke on it last week? thank god for a warranty

 

My car would slip on the 1-2 shift, and in the end broke a 2-4 band. It sounds similar to your slipping coming out of 2nd. I'm no expert, but maybe it helps reassure you somewhat.