MJ driveline vibration

Just finished a whole HO swap into my 90' comanchee, 4.0, aw4, and np231. Everything came out of my running and driving Cherokee. now cruising down the road at about 40-50 mph you get a loud grinding noise. once you let off it goes away. the truck currently doesn't have any tcase linkage or a front shaft on it. I put the rear on stands and tried to simulate the noise. I got it to do it and put my hand on the tcase and that's wheres the vibration seemed to be coming from. I shifted the tcase to 4 hi and retested noise still happened around the same speed. I wouldn't think it would be coming from the trans but I also don't understand how a tcase can go bad like that. any ideas? rear end seems to clunk a lot. I don't know if it could be that?

Theres a tube that goes to the tail housing that provides fluid, if that wiggled loose at some point, the bearing in back could have gotten fried... Just an idea, never heard of an issue like this...

im going to try to get out there to pull the shaft on it to see if the noise continues. ill post up what I find