I installed a 700r4 transmission in my truck. When i went to put the drive shaft on it would not slip on very far without tapping it with a hammer.I had already had the driveshaft cut down. A guy told me it would be ok to shorten the yoke end that slips over the tailshaft.I'm thinking that was a big mistake. Anyhow i got it all in place and drove the truck and noticed the rear seal leaking.Not knowing what year model the tranny is i took the old seal to napa and they gave me a new one.I installed it and drove truck again.It was leaking again. I removed the seal and it is tore to pieces like someone pulled everything out the center with a pair of pliers or something.The first seal i replaced was not in this shape.It was only leaking. After some research i noticed a cup that the yock end slips into on the tailshaft. I'm wondering if this is what was causing my driveshaft not to go onto the output shaft very far? I will check that out but i'm curious why the new seal is tore up so bad? thanks