Rebuilding rear end in TRX300FW

So due to the outrageously priced new OEM rear diffs, after tarnishing my pinion bearing (which led to the teeth on the pinion get all torn up) I chose to rebuild the rear end myself with a full kit that includes bearings, seals, and a new ring and pinion gear. I dissasembled the rear diff today while I wait for new kit, and I removed all bearings, seals, and both gear. I noticed one shim for pinion, and then for the ring gear I either lost one or it only had one and not two (one on each side). This left me with a few questions in my mind. Would a kit typically come with new shims or would i have to buy a kit full of different shims to try and set it up right? will the old shims work with a new ring gear? if i can buy these shims where can I purchase them? Any advice would be appreciated, thanks