06 Toyota highlander "clunks" when backing up. Always in the morning (when not driven for a while) and usually loud for the first 4 or 5 rotations. Then you can barely hear it. Put it up on a hoist and wheel won't do a full rotation before it seizes up and you have to really struggle to get it to move. I want to say you can VERY faintly hear the "clunk" in forward also but when on the hoist seems to turn freely. Replaced gear lube in rear differential. No metal shavings. Any suggestions? Thanks