I have an 04 Ram 1500 4.7 V-8. I had the rear diff serviced, it was fine, the dealer put fluid with friction mod. in it cause my 07 2wd needed that. I noticed a boom when I backed up like I hit something. I didn't think anything right away. I drove it for a week short distances and very little until I thought something was wrong, I took it back and told them I thought it must have the wrong fluid, they checked and said "yep" we messed up. They changed it and claimed the tech found no metal the pinion was not sharp or worn. Said it didnt have excessive play etc. I am getting a rumble about 85-90mph while on the gas if it doesnt shift (ie. head wind) was wondering if anyone thought it was the pinion bearing due to heat or friction since the idiots put wrong fluid in it. Dealer also tells me..."Oh yeah, this truck has the bigger rearend in it, its 10in.). It's so obvious to me they just didnt check the part number on the fluid. Any ideas about the ruble while under a load and accelerating? No other symptoms at any speed or anything. Thanks everyone.

 

I'm not understanding what the cause and effect is here.

They didn't out enough oil or they added friction modifier when they shouldn't have? The dealer can very quickly and easily check the backlash on the gears to determine any excess play or worn patterns.

 

Dang weed.....multipost much?? lol

 

LoL.... Sorry. I'm in a low signal area and on my mobile so I guess it got hung up