Ramcharger vibrates after using 4wd

I will rule out tires. Had new set mounted and balanced yesterday. It is speed related. 45mph and up. The faster I go, stronger it gets. Acts the same with both sets of tires.
I'll check the knuckle joints again.
Thanks!
45 and up is driveshaft. Its easy enough to remove and check. Could have spit out a snap ring.