Vibrations 30-40 mph after lift readjustment

So I got my 6112s re adjusted to 6/5 and now I’m getting some vibes at 30-40 mph. I did the 4hi test and sure enough the vibes went away. Took the truck in to the dealer and they can’t duplicate my issues. I get the truck back and the vibes are gone ‍♂️ So I’m kinda stuck on what it could be and I’m also trying not to grenade my diff if it is the needle bearing. Any help will be appreciated.

 

Put in the ECGS bushing.

Edit: Dont know why I put bearing, meant bushing.

 

How long have the vibes been gone for since getting your truck back?

 

I was thinking just to do it to rule that out.

 

Drove it to work about 15 miles and no vibrations. I’ll see if it does when the truck is cold but idk if that would make a diff

 

Chances are high the vibe will come back. ECGS clamshell bushing for the win.

 

lol yeah ima have to get that replaced. Thanks for your input