acceleration vibration in between 20 and 35 mph

i have had this truck for 4 weeks and it has had a vibration when i accelerate and get to about 20 to 35 mph, it does have a very small lift and i have been told it was from the adda leaf and the carrier bearing. i have put a camera under and i saw no vibration in the carrier bearing but did see movement in the transfer case hope fully some one will be able to help thanks.