grinding 4x4....

I'm working on a 1992 f250 that I have done a f350 conversion on with both front and rear axle. Both being rebuilt along with the transfer case. The truck has a 4" suspension lift.  When the hubs or the transfer case or in gear together or seperate I get a grining noise (as best as I can describe it) when the truck approaches 30 mph...  The faster you go the worse it gets. Sounds horrid!  Ha ha ha!  I pulled the front driveline and put everything in 4x4 mode and got to 70 barely hearing the hubs....  I can't recall if the problem existed prior to the lift or axle swap...  What's the chance the driveline would be the issue?  Any other suggestions would be greatly appreciated  

Bad u-joint in your front driveshaft?