Slight vibration after level

[KRAS]

Truck is a 20 LT Z71 with the Zone 2” upper strut puck level up front and a ReadyLift 1.25” block in the rear. Prior to this I had just the ReadyLift lower strut spacer & stock rear but swapped that out due to CV concerns. 
 

With the current setup I notice a very slight shimmy primarily when coasting.  The current setup was dealer installed & aligned.

 

Anybody experience something similar?

[mafd2]

Almost sure it's the pinion angle.

[KRAS]

Interested- all my experience lift/mod wise up until this point has been Jeeps. I’m surprised a 1.25” difference from stock would cause an issue- you think it wasn’t shimmed correctly?

[mafd2]

I put 2" drop shackles on my RST and had a vibration on decel at lower speeds.  My truck has a factory pinion shim and I just spun it around and cleared up the  problem.  There's a thread on this.  I don't think the 4wd's have the factory shim. Not saying it's not something else with your set up.