humming noise i believe coming from rear of truck

Have the rear end grease level checked. It may be wheel bearings also. It may even be your tires. Try your best to isolate the sound. Have someone in the bed of the truck listen and see if the noise can be isolated to an area. That would be where you should start. I'd place my money on the rear end though for starters. Is this a work truck that hauls heavy loads, a urban drive-around town truck, or one that is used to tow boats or trailers for camping? This will but stress on the rear end. Remember, your truck is not a spring chicken any more and parts do wear out.

mabe your spider gear in your rear end, just had a mine replaced and the noise stopped

I just gave my doughter my 1996 Chevy Cheyenne 1500 pick up there's a humming noise coming from the rear end I checked the oil in the rear end but it's full what could it be.

Buddyromoto: Bearings. Driveshaft, tire, reared, (not likely these are almost bullet proof unless you drag race it with a huge over HP engine.) See if you can isolate it better. Does it hum constantly, or when turning corners, or accelerating? Wheel bearings usually go out first. Drive shaft bearings can let go also, but todays bearings that are sealed seem to last a very long time. If it is in the rear rend, a tear down and bearing replacement may fix it. Look at the cost of rebuilding vs. rebuild swap, IF that is where the noise is coming from.

Question, something is draining my battery and I can't figure out what it is, there's a light humming coming from brand new battery...