Hey guys need some help I just recently bought a 8 3/4 rearend that was suposed to be a a body 8 3/4 but its approx 3 inchs longer then the stock a body 8 1/4 my 8 3/4 mesures 51 1/8" from backing plate to backing plate and my 8 1/4 mesures approx 48" backing plate to backing plate, what kinda rearend am I dealing with? what needs to be done to this to fit in my 1974 swinger and where can i get the right driveshaft or modify the drive shaft I have to fit a 727 torq and my 8 3/4? thanks guys

 

Any info here that may help you? Widths seem to be measured from spring perches and flange to flange.
http://www.mymopar.com/index.php?pid=62

 

Even if you were to cut off the perches and welded on new ones to so that you can bolt it up to your leafs, you'll still have it stick out ~1.5" on either side. You may need to have the tubes cut down to match your 8 1/4.

As far as driveshaft length goes, you'll have to wait til you get the 8 3/4 mounted in and with the vehicle weight on it to measure it properly.