Lowered now feeling those good vibrations

[spdfrk31]

Lowered my 2020 1500 Double Cab 4x4 6.2 using the Bell Tech 2" Front Spindles and 2" shackles. Install was done my a shop and was aligned afterwards. Getting some drive line vibrations at 30 mph and 70mph while either accelerating or decelerating

I have read on the forum about switching the direction of the pinion shim on the rear leafs however mine has no shims. Anybody have an idea on what degree of shim (2, 3 or 4 degree) to install or how to figure it out? I used an angle gauge and measured the degrees on the 

driveshaft per a mechanic friend but don't know how to calculate the numbers. I did hook up a loaded 3 place enclosed snowmobile this afternoon but never got over 50mph. It did seem better at the 30mph range. Getting ready to pull a car trailer to Vegas on Thursday so

want to get this right so i don't tear anything up.

[Bobv07662]

When you installed the drop shackles you tipped the pinion down. You need to use a 2degree shim to move it back up. That's the setup that will get you back on track.