Dusters have an inset rear track. With equally sized tires front and rear, the outside of the rear tire comes close to following the inside of the front tire. Many owners switch to B body axles to correct this with 4.5 inch-ish backspacing. But, @72bluNblu has entered the chat. I'm thankful he posted this one for us back when! An accurate 8 3/4" rear axle width list
Dusters have the same front and rear track width as every other A-body given the same brakes and axles. The sport body cars have wider quarters, so it makes the wheels look like they're further in. But they have the same track as any A-body with the same axle.
A-body 7.25 and 8.25" rear axles are actually narrower than A-body 8 3/4's as well.
The B Body has a perch width of 44", the A body is 43". That's 1/2" wider per side. Most guys don't even bother relocating the perches, they just flex the suspension into place and bolt it up. Not my recommendation, just sayin'.
Yep, why do it right when you can put your springs in a bind and lose some tire clearance too?
I mean, it's not like the rear suspension is important at all.
To me, the number of people that do shade tree stuff like that with their suspension just shows how little performance driving anyone actually does with these cars. If you can't weld on a set of spring perches you shouldn't be swapping rear axles.