Dana 60 front axle vibration

[MixedUpJeeps]

I have an 85 Chev K30 that last year had the death wobble and I changed the upper kingpin bushings and springs, a year later it started again along with a high frequency vibration. I changed the kingpin parts again and added a second shim. The death wobble is gone but I haven't been able to fix the vibration and it is driving me nuts. When I am driving around 40-50 MPH and hit a bump or go over a cattle gaurd I get a high frequency vibration that feels like going over rumble strips at 75. It will stay vibrating until I hit another bump or stop. I have replaced all of the following parts in the last year: front springs, swaybar bushings, upper kingpin bushings and springs, steering stabilizer shock, pitman drag link tie rod ends, right side tie rod end, and have repacked and checked the wheel bearings. Any ideas as to what could cause this ? The tires are wearing well so I think the alignment is good and I'm not getting wheel out of balance shakes. It is also running stock sized tires.