[rgunlock]

Well, on this rear axle I counted 41 teeth on the ring gear and 9 teeth on the pinion. My math says thats a 4.555... or basically not the 4.10 I paid for. I didn't see a stamp on the ring gear here, so I used a sharpie to mark a tooth on each and just counted.

So, I guess this mystery is solved. Now I will give the drivetrain shop a chance to make things right, but since its been 6-7 years, I'm guessing I'll be paying someone else to install 4.10s in this rear axle.

Thank you everyone for your suggestions and opinions!