Well, I found it. Spring wrap. I had shims below the springs to get me to the correct pinion angle, but they are not even as long as the stock spring pads, and since I had taken out the short bottom leaf on my springs, they were wrapping enough under load to cause the vibe. I tested it by putting the ebrake on and pulling the jeep backwards to a tree with a couple large ratchet straps. I then measured the pinion and driveshaft angles and found that my pinion was angled five degrees higher than the driveshaft.
Got some ruff stuff spring perches in today and drove it. Very happy now!
Next up, sliders and rear bumper.
Dusy Ershim this weekend...
Thanks to all for the ideas and encouragement.
Mark
