This is an aftermarket OBX LSD unit installed in a 1995 Mazda Miata case with a 4.1 ring and pinion. I got this differential out of a car I bought for parts. During the test drive it was a little noisy so after removing it I inspected it and found one of the axle stubs was wearing the cover. I don't know why this was wearing funny. Maybe one piece axles would fix this maybe because the car was lowered but I don't really know. When I removed the cover and inspected it I visually could find nothing wrong with it. The ring and pinion teeth look good and mesh well. The pinion bearing and side bearings seem fine. I know very little about these diffs and have no use for it so it's up for sale. The cover is NOT included but is sold separately. $375 plus shipping for the diff. $100 plus shipping for the cover. I also have an RX7 cover for $75 plus shipping.