10 inch backing plates

break down is as follows:
1 1/2 inch=11x2
1 3/4 inch=10/11x 2 1/2
2 inches=11x3
brake gap is very small on "a" body 10x1 3/4. looks like yours is 1 3/8. again, i would guess 10x1 3/4 a body.