Ok, having a huge problem and need some advice from some of you experienced builders. I keep breaking the primary shaft in my Tmax big block. Not sure if I'm doing something wrong or not. I have the Robison Racing slandered ratio still gears, and an Integy aluminum transition case. Is there suppose to be some slop for the primary shaft to move back and forth, or shim it. I shimmer the last one I put in and it broke in 3 places on the 2nd run.