Is this really my problem? on 2002 Chevrolet Avalanche 1500

I was told by a mechanic that my 2nd gearbox in the back drivers side is the cause of my car making a loud hammering sound. But this was after he told me it was a differential? He also mentioned something about pins going out? I'm the worse person to speak car terms with:-(I don't know if the three things work together or connected in any way but he came back with a quote thats more than my mortgage. The hammering sound comes on for about 5 seconds then it'll stop, all you hear after that is the sound of grinding brakes. He went on explaining that the pins where the brakes rotate were out...I couldn't make any sense of it. What could my problem be? Is it possible that it's just the rotors that I need to replace? Or it is something that I could maybe fix on my own? Is a differential tied to the gearbox and pins at all? Any help would be greatly appreciated. Thanks in advance for all your help.

by in Federal Way, WA on April 25, 2011
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1 answer 1 comment
ANSWER by , April 29, 2011
What you have told me really doesn't make much sense, I don't know what you mean by the "second gearbox" (maybe you mean the rear differential). I'm not even sure what the complaints or symptoms are. I don't think you're the person to work on the vehicle since it doesn't sound like you have any knowledge of the subject. No offense intended, but automotive work is not easy to do or to learn, and if it's not your thing, don't feel bad. My mechanic career certainly wasn't too glamorous.. If you don't understand your mechanic or don't trust him, find an independent GM specialist and get a diagnosis and estimate. If you want to find a specialist, here's a directory link for you: https://repairpal.com/directory?address=98023&car_brand_names=Chevrolet
COMMENT by , April 29, 2011
Thanks Superbob. Got another mechanic to look at it and was told that it's the rear differential. Estimate 1279 with labor:-( Big ouch! Thanks.