ok here is the background, truck is lowered with springs up front 2". rear is lowered with shackles and hangers (belltech) with a carrier bearing relocation kit. possibility of one noises here. (pinion angle)(how to check) i have an eaton, and aftermarket gears. possibility of second louder hum on deceleration or tq converter?

i get a hum when just cruising and i can feel it in the pedal slightly. then when i decel i hear a louder hum. if i accelerate the first hum goes away. but when i coast the other hum gets louder. wtf is it. it really doesn't sound like gear whine but i am going to check the fluid level tomorrow to ensure it's full. i haven't really had time to look and inspect anything. it rains here every day lately and i have been dealing with personal issues. give me some ideas to save time.

 

Man thats about what mine did.. it was comin from the Diff bearings. so i put all new bearings in there.. Prob fixed... Cost= $100 that was for all the bearings, seals, pizza, Drinks, and ice..

I could see the problem when we took the bearing off the G-80.. the inner races looked like some one had taken a hammer and beat the crap out of the bearings,, imprinting them into the inner race.
Im guessin when it was strapped down or from some of the heavy crap ive hauled, done it. Ive had almost 2500lbs in the bed before. but i dont see how it could have messed up the diff bearings, and not the wheel bearings also...

But here is what i did to find the culprit.... jack the rear off the ground, Crank her up and place in 'D' let it idle.. it will prob get up to 35-40mphish.. get you a screwdriver, Place end of screwdriver where the diff bearings are place your ear firmly to the end of the handle..

kindof like a redneck stethascope (sp). It works though so dont laugh.

 

Rear gear. Possibly the lash. My 06 with no mods to the rearend has a hum to it while coasting. Slightest bit of pressure on the gas pedal loads the drivetrain and no more hum. My .02

 

when i set up my ring gear, the lash called for was .008 to .012 and i think i ended up with .012 (max allowed). i have a slight hum but you have to listen for it.