18" Wheel help
perches need to move in 1/2" on each side (center to center is 43" for A body, 44" for B)...if you already have an 8.75 or even an 8.25" rear, the driveshaft should work.
the B body rear being 3" wider will limit tire size in the back unless you go higher offset. when I measured clearances on my duster, the stock SBP 7.25" was 57.125" wide, and the wheels were almost perfectly centered in the wheelwell. with a 60.125" rear, with typical mopar +1/4" offset (4.25" backspace on a 7" rim), anything bigger than a 225 out back would require trimming or rolling the rear wheelwell flange on my duster