I understand your statement, but please understand I've had this issue since 2005. I would think it it were a loose bolt or bushing, it would be "better" coming out of the shop then get worse again. Being a bushing seems it would progressively get worse.
It's been to 2 Dodge dealers, a frame/front end/4x4 shop, the best alignment shop in the city. Does this truck have some sort of king pins like old fords?

 

I would try removing both front axle shafts and the front drive shaft, then stuff something into the axle tube to keep debris from getting in there the drive it to see if the problem is still there.

What are the chances that the transfer case is momentarily engaging (without the CAD unit moving the shift collar) or that the shift collar is momentarily slipping onto the passenger axle shaft while driving?