Reverse Slippping
 

I have a 1995 Blazer 4x4 with 148k miles. It has a reman trans in it with a new torgue converter 25k ago. I have 2 issues and thinking they are linked.
1: When I put the truck in reverse is slips a little then a light clunk like it enaged. Then it backs up fine. Takes about 3 secs for this to happened. Ive done a filter and fluid on the trans and also pulled the differential and new fluid there. The truck drives fine in 1,2 d od.
2: The other issue happens spractically. Ill be driving down the road and then a loaded humming sounds comes from what sounds like the right front. This sound sounds like a plane landing right on top of the truck. When it first happened I thought it was a tire going flat for seperating. It will do this noise for a few seconds then a clunk and it stops.

Im wondering if this is a sign of a transfer case problem or front differential problem. If it was a transfer case would it act likes the trans is slipping for the first issue. I replaced a bunch of vacuum lines but didn't look at the trans or diff's.
Any thoughts would be appreciated.