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

As old as it is there is no telling what changes have been made to it. But the center to center on the leaf spring pads is 43" and I see no signs of them having been moved, so I feel sure it is an A-body 8 1/4. Maybe the 11" backing plates were put on there at some time. Does anyone know of anyone making the 8 1/4 ring gear 1/8" spacer these days?