I haven't figured it out yet, but the next thing I'm going to try is swapping out the drive shaft, just to make sure that's not what's causing it.( I had it balanced back when this all started and I just want to be sure they didin't screw something up). I've found out that if I run with the hubs unlocked but in 4 wheel drive, it still vibrates but it doesn't get real bad. It's usually around 65-70 MPH when it's the worst. I'll get back with a post as soon as I get some time and ck it out...: