yeah, you're dealing with a 4x4, so you need your rear gear to match the front gears. Otherwise, you can find 10 bolt rears for $100 that run. Sure they're used and you never know how long they'll last but axles really do go for a long long long time. Usually what kills them when they have been properly set up at the factory, is they get worn, then people do burn outs and such and break them. Otherwise, even a wore out will get you across country if you can tolerate a little bit of slop between drive and reverse. Running them low oil tends to wear them out quicker too, but still, even low oil isn't a killer like running a motor without oil. You can always tell when an axle has been run low on oil for to long. It'll usually howel like a wolf at freeway speeds. If you buy a used one and the gears aren't broke, and it don't howl, you can expect it to get you by for a good long while with some new oil and if you don't do burnouts and abuse it and such. Axle assemblies really are pretty strong and tolerate quite a bit of abuse and will run wore out and not leave you stranded if you're willing to tolerate the howling and clunking. Kinda like an old man with his joints creeking and cracking. He's wore the hell out, be he keeps on going.
