Q45 differential question

[carlosinseattle]

I have a 94 Q45a w/tcs 141K miles.

I bought this as a project car, and I think the previous owner put a "better" differential in the back end.

What are the gear ratios of the two, or more, different differentials you can use in this car?

I'm getting a couple of codes that lead me to believe the differential is the problem. And I doubt it's the original differential by the yellow paint that's on the diff. It looks like it was in a junk yard or parts house then installed in this car.

FYI, I'm getting right rear wheel sensor, which I've checked 15 times, as well as tested all the wiring in the TCS system for continuity and resistance.I'm also getting vehicle speed sensor, which I replaced with a brand new one, form the transmission.

That's why I'm thinking it's the diff. I changed the wheels and tires, and I don;t have the old set. He may have compensated with different size tires on the rear to "trick" the computer into thinking it was the old diff.

Or maybe I'm totally off base.

Please help....