Having same issue.
Ok, i am going to start from the beginning. Ill start by saying I am fairly average on my knowledge of vehicles, but fairly dont know a lot on rear diffs, except for the general parts used etc.
My 2000 durango was in the shop for rear breaks, mechanical told me the rear diff fluid was really low, so he topped it off, he said that the leak should be fixed, with parts and labor, about $60. So i brought it in a few days later to him to have it fixed, he gets back to us a few days later and says the rear end has some problems needed to be fixed, we told him to go ahead, (he said things about the pinion bearing and something about the wear pattern on the teeth of the gears). I had noticed the whining sound maybe people have described prior to it going in, it whines when you accelerate, but if you are coasting, its almost nonexistent.
I get it back a week later (parts took awhile he said), and charge us $711. He showed me a box of parts he replaced, i saw the pinion bearing for sure, and a bunch of spacers and other small parts? No gears tho. I drive away and already its whining, and whining loud, louder than before. Way louder than before, 2 or 3 times louder, but still goes away when coasting.
I only put about 50 miles on it since i got it back, and it sat in my driveway, and its still leaking from the rear diff, he couldn't even fix that!
Also, when driving it, it starts to smell a burning smell from the rear end(this also started happening the day before it went in, but i had to drive a lot further for it to start making the smell), like i said i only put 50 miles on it so far, and always only 10 or so miles at a time; im trying not to drive it when possible. I dont know if that would help with a diagnosis.
Basically i just dont know what to do. Ive been reading all different forums all day. I dont know if i have a LSD? I read somewhere that they didnt put in the friction modifier in the rear diff and it made it whine, they added it and it dramatically decreased? could this be all it is? any thoughts?
what should i do besides go to a different mechanic????
is it just a spacing issue??
I just dont want to get screwed again
Lastly, the only reason i went to this guy is its a friend of my dads and usually gives us a good deal on labor costs. Im starting to think he might be incompetent when it comes to rear diffs?? This $711 seems really high from what ive seen elsewhere online. I kind of go through my dad, my dad tells me what he says, and how much it is, etc. We havent paid the mechanic yet, if he cant fix it, shouldnt he have told us he was over his head?? i mean, he couldnt even get the rear diff to stop leaking??? Im just torn, i dont want to pay him. All he did was replace parts, that if left as is, will just get warn and break like the last ones, except faster? and maybe even ruin other parts of my rear end.
I really appreciate you sticking around to read it all. thank you for any help you might be able to give.