ok, i have my stock 7.5 rear that i have sittting with a posi and 3.42 gears. can i get by with just a new crush sleeve, proper shimming and cover seal? or should i replace all bearings and seals? i have never really heard of bearing failure on a rear end and i see no signs of needing to be replaced. i am new to rear ends but i need to get this doen and i am also going to be doing the 7.5 in my cutlass next.