Rear Axle Mystery Failure HELP!

Car: 1992 Rodeo V6 4WD 5spd 180K

Problem: I brought my car in to have the Rt rear leafspring fixed. When my mechanic put it up on the jack a ton oil leaked out of the Rt rear wheel assembly. (imprecise description, I know) He took the wheel off, looked at the axle and saw major wear. Looked like it had worn through the hardened steel on outside of axle and was cutting into softer flexible core. He tried putting on spacers that apparently work with many truck axles, but didn't fit. Couldn't locate new axle so sent the old one out to a machine shop in Binghampton. Also had to replace brakes.
Over $1000 and less than 1000 miles later, I start feeling bumpiness when I was braking. I take a look at my tire and there's oil all over the wheel well. Sent it back to mechanic and he sees the axle's worn through again. At first he thought it was bad work by the machine shop, e.g., failure to harden the axle properly. But the machine shop claims they did it correctly and that the problem is the rear axle assembly. They suggested that something in it is causing the axle to wear out quickly.

Now my mechanic is telling me I need to replace the whole rear axle assembly. He estimates $950 for the part and $600 to fix. I'm inclined to trust him, my Dad's used him for years. But I recently went back to school and I'm way too poor right now to come up with $1500.

a) has anyone heard of this problem?
b) any idea how I could check out whether he's right? (i.e, that the problem is the rear axle assembly)
c) if I do get a new used rear axle assembly does it have to be from the exact same model? (I saw a 91 V6 4wd automatic)
d) any clues on where to find salvage/parts cars on the east coast?
e) should I junk it? Or try and sell the parts piecemeal?

thanks
Quasar

Thats one hell of a wierd problem to be coming from a rear end. The only real way to find out if your mechanic is being honest is to try a couple other shops and see what they suggest.

If you get used rear axle assembly make sure its from the same vehicle that you own. If you get a rearend with a different gear ratio than what you currently have, and try to drive somewhere in 4WD your in for some trouble. The ratios have to be the same so just make sure they are before you buy anything.

I saw that I had oil all around the Rt rear whell. I thought that my Rt wheel cylinder was leaking, so I changed it last week. Today, I saw a ton oil again, I realised that it was axle oil. I bought a new seal, but my axle is wear. I have the same problem you got and I don't know neither what to do. I have a Rodeo 92 v6 4WD auto and
180 000KM