irv

I might buy a 2001 2wd Tundra that needs a new rear diff. Is this a common failure for these trucks? The owner says that the diff gears grind if you try to drive it. The truck's gears just turn and grind but the truck goes nowhere. Are used or new differentials relatively easy to come by? Expensive fix or not too bad? Are differentials from the 86 to 95 pickups interchangeable by any chance? Or perhaps would you possibly need an entirely new rear axle assembly for a situation like this? There's got to be some real carnage going on inside that rear housing if the gears just spin and the truck doesn't move.