What A-body did this 8 1/4 come out of?

So here is the st6ory. I buy some parts from a guy not real far from me. In all this stuff, I buy is a 8 1/4 rear that I was told came out of a 73 Duster 340 car. But here is where it gets a little weird. It's definitely is a 8 1/4, the casting number is 2852905, the spring perches are 43" apart which is correct for the A-body. But the brakes on this rear are 11" x 2"? Nowhere that I have been able to look show an A-body rear ever coming with 11" brakes? The housing measures correct for being out of a A-body, flange to flange is MOL 51 1/2". The bad news is it came with 2.45 gears which sucks, and the Sure Grip I got with it is for the 2.45 ratio or higher. So I'm looking for a 1/8" 8.25 ring gear spacer ,if anyone has one they want to sell. Any help would be appreciated.