Hi all,
I got a real mystery noise that would love some input on, I just bought a 2013 Ram 2500 with the 6.7cummins with 74000miles, I had the dealer put a 4inch BDS lift with 20" motometal wheels and 35" tires and since the lift has been on I have a real odd light knock/loose slap(if thats even a description) that sounds like its right under my feet, it starts a 38mph, is at its worse at 48mph and goes away around 65mph, its not a fast noise and I really can't feel it through the floor its just more of a noise at this point, if I'm going around 50 and flip it in 4wd as soon the the 4wd engages the loose/slap/knock noise goes away but then I get a high speed vibration and hum. I had a shop inspect it and ended up putting a new front driveline, 2 new ball joints on the driverside and both wheel hub assemblies and they re-balanced the wheels, I was hoping all that would have taken care of the noise but its still there.

I had the truck for about a week before they put the lift on and never noticed any noise at those speeds before but noticed it immediately when I drove the truck out of the lot. this weekend I am going to check and verify driveline angles pull the front driveshaft and run it without and check for loose axle ujoints and eventually I am going to pull the diff covers and inspect them and check the transfer case fluid for metal or debris but wanted some feedback, I want to rule out a diff/transfer case issues due to the fact if there was a problem there I feel like it would have been doing it before they put the lift on it but I work in a heavy duty diesel shop and know anything is possible. TIA