Rough Country 3" Suspension Lift

I had a locally respected garage(Cap & Hitch Westspringfield MA)that works with the local Toyota dealer install this rough country lift and I am desperately reaching out for anyone with any knowledge about this particular set up on this truck. FROM THE MOMENT OUT OF THE LOT when my lift was installed I have a vibration at about 20MPH and 40MPH coming from what I think is the front differential. I tried to have the dealer look at it but those assholes wont because it voids my warranty. I had cap & hitch take it back and they put a spacer under the driveshaft however this did not fix this issue. I had a third party call endangered species in holyoke MA look at it and he said there seems to be alot of play on the axels entering the front diff so he thinks its possible that I have bad bearings in the diff. I have 21k miles on this vehicle I work and go to school in the same town I live in I have not drove this truck very much millage wise I have Babied this thing and its bone stock other than this.everyone I talk to says that would be very bizarre for my diff bearings to be bad this early. Rough country is sending me a 4" lift FREE because of all the bizarre shit im going through however that lift requires cutting of factory brackets in order to install and is not easily taken out if I end up having the same vibration issue. The 4" comes with a diff drop and claims to set the truck back to "factory geometry". I have decided to pull out the 3" and see if the issue is still there because I have only had the lift installed less than a month so the dealer said they would investigate if the lift was removed. my plan is to do that hope it goes away and then either put that free 4" in or find something else because I already spent $2000 on new wheels and tires that wont fit stock!! anyone have any recommendations for this fucking bullshit Im dealing with lol. First time on this web page sorry the post is so long but clearly there is alot to unpack here. 2016 TRD sport 4WD long bed.

 

On this forum there a lot of ppl changing out the needle bearing to ecgs bushing, trying it out in 4 hi, if it goes away then diffidently the needle bearing