The yes u joints are new and driveshaft is new. It had vibration after you crossed finish line and left off in 1/8 mile for about 2 seconds. Adjusted ladder bars and now have vibration 20ft before finish line in 1/8 mile.

Thats from having too much pinion angle.. as you let off
the rear tries to roll down but being a ladder bar its
sorta stuck there... the correction in the pinion angle
will take care of that... if you still feel it some you
might have hurt the U-joints or the drive shaft.. you
can go even less on the pinion by .5*(roll it up to 1.5*)
EDIT
Also.. how far is the drive shaft from bottoming
out in the trans... should have 3/4" when sitting

Yes i have 3/4 to 1 inch from bottoming driveshaft

Is the rumble from your lack of rubber bushings? Heim joints will transmit alot of noise.

I understand you trans to driveshaft is limited by the transmission. Can you lower the engine?

There is the ultimate rear universal joint angle and thankfully with ladder bars, it's a small number but like every adjustment it's a comprimise.

We aim for -1 to 0 deg pinion down for ladders for drag racing but when smooth is the goal it's two small angles like a max of 2 deg and matching. When a universal joints runs at an angle the driveshaft slows and speeds up everytime the cross moves. If the angles at each end match the slowing down and speeding up is cancelled at the other end.