So I have a 71 duster that I have a c body 8 3/4 complete unit from a 65 Newport. I want to narrow the housing to be a little bit narrower than a stock a body width. What did you guys do for axles? Is there a way to modify the stock axles to become shorter? I will be putting a 440/727 combo in it with 3.23 gears and want it to hold up

I called Doctor Diff and ordered a set for the shorten housing.

Just did the same thing on a 69 Dart. Order the A Body 4 1/2" bolt pattern conversion axles from Doctor Diff. They are splined deep enough that you can shorten them. We shortened the ones I bought 1" on each side.

I sent a 1/2 ton truck 8&3/4 housing/axles in to Moser in Portland Indiana for shortening to A body specs. As far as axle selection they informed me that if you hook a tape over the flange & have 28" or more out to the end till the axle starts to taper that you have a suitable candidate for narrowing to stock A body width & less than 28" if you are going shorter than stock A body width. there can be a stackup of tolerances & if I was to do it over again I'd mockup the axles with foam/steel gaskets/backing plates sans 3rd member & measure the distance between the axle ends in the bare housing & give Moser that dimention

Ar RR said, the OE axles can be shortened and re-splined up to a point. That said, if you are planning power and hard launches, stock axles are a weak link. Step up to a stronger aftermarket axle helps and may not be much more expensive than re-spline with 2 way shipping.

This might help: