aspen rear

The 8.25" F body rear axles are 54.34" flange-to-flange, and the perches are 44.5" C-C.

So, that's wider than the A body 8 3/4's which are 52.625" flange-to-flange and have the perches at 43" C-C.

That said, a wider rear axle works well in the Dusters/Dart Sports/Demons. I have a B body 8 3/4" in my car, and its 54.9375" flange-to-flange. Works great, you just have to move the perches and have the driveshaft shortened to fit the 8.25. I think it would be worth the upgrade if you're running anything other than a /6.