last time i talked to chase, he couldnt get any of the shims for a 300. Ended up cutting my own out of some shim stock for the front output, and mcmaster sells an assorted thickness set that the ID and OD will work on the rear output.
I've got a few shift rod seals if you need, I bought some extras on the last project. They are only bucks from quadratec though. Which shims do you need, for the yoke, or for the front output bearing preload?