Motive gear ring and pinion

Street driving, with a heavy foot...

Is it going in a Dana, 8-3/4, 8-1/4? Just wondering. I recently bought a 4:10 for a Dana from Summit. It was a Richmond gear and it did not fit -- not even close. Returned it to Summit and they only gave me half my money back... Long story.... I was just trying to save you the same problems I had....