When you pull the carrier, it's vital to keep the shims separated so you know which side they were on originally. Sometimes, depending on which type of axle you have, you can reuse the original shim packs, and sometimes not. No matter what, mark the original shims so you know the dimensions. In this case, we replaced the original one-piece shims with Randy's Ring & Pinion Super Shims. The kit comes with two hardened faces between which you stack smaller shims to make up the exact total thickness you need. That eliminates the need for lots of shims in stock.