If you are in AZ, ship a core to @NicksTransmissions in Las Vegas. It is your safest bet. If you watched some of his videos rebuilding a new "HD 700R4" that melted down, you'll realize all you are paying for sometimes is stock parts and black paint when you buy them through the mail. Would have cost way to much for me from the east coast, but maybe parts labor and shipping would be close to $2,500 and you at least know what you got.
Don't buy anything from Powertrain Products. I am on my 4th rebuilt transfer case from them (all under warranty). All 4 immediately leaked as soon as they had fluid in them without moving the truck an inch . Remove and install was on me for all 4 (god I hate that job). #4 leaked too, but it stopped for now so I am going to let it ride just because I don't want to deal with the job again right now and I still have a 3 year warranty if it comes back or gets worse.