I honestly don't know, I bought it as a shell but was told by the previous owner that the entire drivelin including the diff has already been rebuilt. It didn't leak, and I don't know enough about RX7 rear ends to say for sure whether it has been opened up. You are welcome to come over and inspect it. I do know the car had not been under it's own power for more than a handful of miles for the last dozen or so years. It was in a barn for 6-7 of those without an engine. The guy I purchased the car from bought it from the original owner.