well i put a salvage rear end in a couple months ago. worked fine for a couple weeks but i am getting the noise back. when i get up to about 40-55 inside the truck gets like a deffening like rumble noise and it will start randomly jerking for split secs and make a louder vibrating noise, but after i get past that speed it all goes away. idk if its my u joints or maybe the axle bearings. Im really stumped on this one.