H2BSTUPID

hi, i have a evolution h2b set up and in one month i have torn up the splines on 2 clutches, i am thinking that maybe its the input shaft that might be worn down??? i am not an expert to tranny's so if anyone could help me out and let me know if this has happened before??

the clutch and all worked great. I have a bully stage 5 unsprung with a reinforced stage 3 pressure plate, the motor just has basic bolt ons.