Metallic buzzing sound??

So tonight I drove to the supermarket and when i backed out of the stall my truck made a thump sound. I continued to exit the parking lot and merge onto the road when i heard this sound coming from the front driver side wheel. i don't know if its on both sides, but it makes sound only when i shif to 2nd gear and up. Radius arm bushings? or my automatic hubs? could it have anything to do with my automatic hubs? because my truck pulls to the right now.
first real problem i've had and i've owned it for almost 3 years.
help would be much appreciated.
thank you.

sounds like a stuck brake. does it pulled to the side while driving?

sounds like the hub if it starts grinding. Put it in 4x4 to see if it stops. If it does or does something different you have found your problem.

yah, it does pull to the side when driving. brakes work fine still.

sounds like the hub if it starts grinding. Put it in 4x4 to see if it stops. If it does or does something different you have found your problem.

good call on that. the other day i got in my truck to see if it would do the same thing as the night before, and before i drove off i put it into 4x4, then turned it off. when i drove away everything was fine until it started acting up again. i took it on the road and ran it up to 5th gear and it was fine. took it over some speed bumps at normal speed. turned a right corner to go back home and then it started up agian. makes noise above 2500 rpm.
i'm going to take a look at everything today on my day off, and then take it to a garage or soemthing... the fear of the repair cost is what frightens me.

Price is a big issue with the auto hubs. I know of several cases where the owner opted to install aftermarket manual hubs due to the cost of replacement autos. They are very easy to change (I'm assuming you have a '94 or older). Pull the wheel, snap off the lock rings (if they're still there), slide the hub off, pry off the plastic inner piece, slide the new hub on. If I missed any clips or snap rings in my procedure, it's spelled out in the instructions for the replacement hubs.

Heres what to do if the hubs kick in. Pull into a parking lot and back it up for say 10 or 20 ft and hit the brakes. This should disengage them. After you use 4x4 always back up to disengage them. THey won't fully disengage going say 10 or 15 mph. Also always engage 4x4 in park or the hubs will spin out. i know you can supposedly do it while moving but from my experience with mine do it when you are still. Good Luck with it.