2010 camaro, 600hp with centri, 3400 PAS yank stall, 3.91 gear, 6l90 swap with extra clutches. This is my second factory intermediate shaft I have broken within a week of each other. Between 3-4 shift it breaks. What usually causes this? I am following tuning school trans book, with added oncoming presets 0=300 1=500 2=800, car shifts great 1-2 and 2-3 but 3-4 is quick but seems smooth under light throttle? Do i need to change my volume presets or something, do I need to just buy a billet shaft or go back factory?