Replaced rear driveshaft u joints and while I had the driveshaft removed from the transfer case side, I put the truck in neutral while running and Hurd a loud grinding noise? Never had this happen to me did I break somthing or mess somthing up? Thanks Kyle

 

did you let it run with no load on the transfercase?
Could have been the chains inside being stupid.
*shrugs*

T-cases are weird with no load.
I've done this before though and had no issues. so .... *shrugs*

Drop the T-case fluid and see if its nasty or parts come out.