A-Body 66 Barracuda 8.75 backing plates

Different backing plate between the 7 1/4 and the 8 3/4.
Although I was always under the impression that the lower hole can be drilled to make it useable on an 8.75... I've got a 7.25 with 10s buried in a corner of the shop, but I just REALLY don't feel like digging it out and pulling it apart just to find out. :(