ORIGINAL: crashhard23

i have a question for who ever can help me.this is my first truck.and found out that one of my bevels had little groovs on the teeth. When i get the HD 13t and the HD 38t set,what exactly do i have to shim. i hear that if i want to go full hevy duty that i have to mod drive cup to fit. what do they mean wich cup and does any one have a step by step or pics thanks. i need to know what shims i need and how to do it thanks

oh yea i have the mt 2 with the t15 engine