Vibe issue. Will this fix it

99XJ

All was well untill I did a Bastard pack in the rear. I ended up at about 3" over stock. It rides stiffer than it did and i get vibes at 70mph up, and between 30 and 35 under throttle.

I scored a set of 1.5" shackles at the junkyard and was thinking of taking a few leafs out and putting the shackles in to sit at about the same height. Hoping the shackles will give me enough shackle angle to help the vibe issue. Think it will be enough?

Well you have a 97+,which means possible vibes even stock.Check your angles and save for a SYE kit!

Shackle angle doesn't change vibes, pinion angle does. Pay attention to the gas pedal when it vibrates most. I'm guessing under throttle at 35mph? That would indicate the pinion needs to go down, not up.. which a longer shackle would point the pinion up more.

Problem is that pointing the pinion down more in order to get the tcase output parallel with the pinion pulls the driveshaft even further off the tcase and increases the ujoints operating angle. Even if the angles are dead nuts on you will probably get unpleasant transient vibes as you pass through neutral throttle, but should be vibe free the rest of the time.

SYE time..