10 inch backing plates

The short answer is no, you need a knuckle designed for 10" drum brakes. The
more complicated part is would you be able to use your belvedere knuckles w/the
'73 and up upper arm/large balljoint. NAPA list's the same lower and upper ball-
joints for your B and the '73& up A w/discs, but I'm not sure about the knuckles
heights/angles being OK. The width of the 10" A vs B shoes also will factor in.
Early A's had I believe 10X1.75, not sure about the '66 B width, but later were all
10X2.5 . Later A's '73 and up also went to that size. Unfortunately my old catalog
isn't quite old enuff.