I’m doing a fairly budget build/V8/4 speed swap on my 73 Duster. I believe I now have everything for the swap. Here’s what I have and what I’m hoping might work. Seeing as a stock A body 8.75 in a Duster leaves a good bit of room to the outter wheel well, maybe I’ll be lucky and this will fit. It would be nice since I have all this stuff from years of collecting. Thanks!!

68-70 B body 8.75
7” Police wheels

My perches are right at about 44”
It’s hard to measure with the chunk in... but from flange to flange (housing, not axle) measures 55 1/8. I’m positive it’s shorter than that because I had to bend the tape a hair to get to the other side.

for flange to flange you could take 2 pieces of dental floss with a small nut tied on each end & affix em to the flanges, hanging down to your bench then tape that distance between em but likely someone will have an answer for you on this fairly soon as I've seen it posted before.

I saved a thread from a while back but can’t seem to find it.

I use a piece of new brake line and bend it so it matches where I need to measure. You can easily go around whatever might make it hard to measure with a tape.

The stock B body 8 3/4 rear ends are right at two inches wider than the same year A body are

The chart I have shows your stock axle would be 51.4" flange to flange and 43" spring width. A b-body is 55" F to F and 44" spring width. Looks like you will need to change the drive shaft also.

Please kill that chart, it's horrible and wrong on a bunch of measurements.

A much better reference...

http://www.moparts.org/Tech/Archive/axle/16.html

Stock 68-70 B should be 60.125ish wheel mount to wheel mount. 44" perches are 1" wider than an A at 43". Lots of people pull the springs to get B rears installed.

It may fit OK. Wheels tend to need a bit more backspace than the stock mopar wheels with a 68-70 B rear in an A body. Dusters are more forgiving than Darts.

Thanks for the new info. I just measured a housing I have and it didn't match anything on my chart.

The chart isn’t very accurate in some applications. I think I will be ok but it’ll be a little close. Thanks guys.