Which one would be the proper width, 70 B body?

Thanks!

I think the NHRA stocker guys use to use 1967 to 1972 A body 8 3/4 for their Volare and Aspens

Friend put a late 60s C body rear in his.

66 or 67 B Body. spring pads are > 1" difference from stock. the slop in the bushings and chassis allow a direct bolt in without modifying the axle. You need to remove the leaf spring isolators too, i used my stock F body main leaf and added the spring pack from a 67 BB B body with a new through bolt

here's my build little info on the rear though https://board.moparts.org/ubbthreads/ubbthreads.php/topics/2116859/1.html

15x10 3.5" backspace 295 50 15 tires.

Thanks for the replies.

I also used a 66-67 B body rear in my 80 F body with the same year B body main leaf and the balance of leaves coming from SS packs. These years are 59.5" wide. 68-70 are 60.125". This may create possible fender lip interference depending on your choice of wheel and tire. I also dumped all the iso-clamp system for conventional spring eyes and shock mounts.

I had 15x8 Dragstars with 4.5" backspace and a 295/65x15 tire. Had to severely roll and hammer the fender lip up and it would still kiss the edge of the tire on dips. You can see the thin shiny streak on the shoulder in the pic below.

Yep those B body ones are the closest. One of my Ms has 255-60 tires on it's 8 3/4 that fit no problems, might be an issue if the springs are sagging,

We put a 70 B Body housing into a 78 Aspen with no problems, set right on pads

Here's info somebody posted before:

Factory axle dimensions (7.25" and 8.25") for all F/J/M cars:

•Housing flange to flange: 54.34"

•Perch center to perch center: 44.46"

Here's the '65-'67 B-body specs:

-Housing flange to flange: 54 1/4"

-Perch centers: 44"

the 66 67 B body is as close to a straight up swap as possible to the F body.

If you still run the ISO setup then you can use a 1 9/16" hole saw to open the spring perch to accept the locating pin and rubber isolator combination. Just bolt a plate to the underside of the spring perch so the arbor has something to bite into.

You can move the springs far enough a 66-70 B body bolts right in. If you are worried about the slight perch difference? Move the rear shackle hangers. Pull the bumper with its supports. You can drill new holes in the frame rail and mount the shackle inward and forward if you like. Each drum will be 5/16" further toward the outside. Using a 727? A 727 driveshaft from a Duster fits perfect.
Doug

I used a 68 B body 8 3/4 in my Mirada. It was slightly narrower than original 7 1/4 but pretty close. I got rid of the iso stuff at the same time, but it went on the springs no problem. I know on paper there's about 1/4" difference per side but as I remember I ddint have to force anything at all.
I had 275/60's on 7 " cop wheels at first but the 4 1/4" backspace put the side wall very close to the inner wheel wells. 8" wheels with a 4" backspace fit a lot better.