Hello,
My 72 Duster currently has a 318, 4 speed OD tranny and an 8 1/4 rear out of an F-body(wider), and I'm looking for a new stock width or narrower rear to replace it. Will the driveshaft need to be swaped if I go from an 8 1/4 to an 8 3/4 rear? If so does it need to be longer or shortened? I havent found one yet but I want to get all my info together. The car has the springs moved in 3"s on each side and I plan on mini-tubbing it and with the 59 1/2" rear in it now it would be almost imposible to find wheels with that much backspacing. Thanks

Butch
Hazlet, NJ

you'd have to shorten your shaft, but you probably have the small u joint anyway. Time to step up to a bigger u joint anyway. Go with an aluminum shaft

Ok, thanks, figured it wouldnt be the same. Yeah I dont know what the current driveshaft is now, I would quess the small u-joints with a 318, but I'll have to check. What does a new driveshaft cost, ballpark?

Butch

That size corresponds to a C-body rear end, A-bodies are like 51.40" F-bodies 54" you can have a driveshaft shortened pretty easy if you check the yellow pages for driveline shops. Good luck.

The rear is 59 1/2" from the outsides of the drums or wheel mounting surfaces , I know the A-Bodies are around 57 1/8 drum to drum, so I figure a stock A body or narrowed rear would work good, something 52-58" Drum to drum maybe.

Sorry I did not see drum to drum not backing plate.

http://www.moparts.org/Tech/Archive/axle/17.html

Yeah its only a mildly modified 318 and aluminum 4 speed od tranny. I do plan on building a 408 stroker in the future but thats a ways off(probably 2 years ), plus I dont know if I'd stick with the 4 speed or go with a 727 instead. I would guess that the driveshaft length would be different with a 4 speed and a 727 tranny, right?

Yes, the 727 tailshaft is longer than an A-body 833 tailshaft.