So driving down the highway about 3 weeks ago my front differential started clicking, which rapidly progressed to thumping and eventually car shuddering thwacking in the space of a couple minutes. It blew the ring gear and fractured the case.

I had the trans rebuilt by amco last summer(second time in 2 years), and my understanding from the shop owner at the time was that they just couldn't get it right(took over 2 months) and eventually ended up completely replacing the whole unit, which almost always includes the front diff. But he only charged me for a rebuild, and that's what went on the paper. So I go back and the place is under new ownership, and they say the warranty doesn't cover the diff cause they only did a rebuild of the trans. These people were there last summer and I'm certain they know otherwise, but screw it, I can't prove it and arguing it out isn't getting me anywhere.

Their first reaction is to accuse me of impacting the diff case(bottoming out) when anyone who knows anything about what happens to aluminum when it impacts something on the bottom of a car can see that they are completely full of it. After finally taking the thing apart they tell me they can't find a replacement diff anywhere. I get the guy to agree to use a diff I supply If I can locate one. So I get a very nice deal on a burnt trans with a good diff from the nice folks at motorsport warehouse, and deliver it to amco. When I drop it off they all start asking me if I got the right "gear ratio" because apparently svx differentials come in different flavors. I call up motorsport and they tell me they are 99% sure there is only one flavor. I don't know much of anything about differentials or automatic transmissions, Help?