will a f/m/j body 8.25 rear fit my duster

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gomangoduster

gomangoduster

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looking for alternatives to 70-76 rear ends as there are none to be found here. so maybe jeep f m or j body 8.25 rears does anyone have any advice?
 
same question. i located a 8.25 from an aspen R/T. will this fit on an A-Body. anyone know the width of this?
 
gomangoduster said:
looking for alternatives to 70-76 rear ends as there are none to be found here. so maybe jeep f m or j body 8.25 rears does anyone have any advice?
Click to expand...

The axle length on the F/M/J will fit between the fenders. The spring perches will need to be moved. The spacing on an A-body is 43 inches. The F/M/J is 44 inches. Move each perch in ½ inch in on each side to make it fit.

Haven't poked under Jeeps enough to know if the axle is over or under the spring on all models. If the spring is over the axle, you'll need a perch on the lower side of the axle. The Cherokee tread width is significantly more then the A-body, you may be able to get some of it back by increasing the backspacing on the wheel.

If you're not a purist the Phord Grenade rear axle (8 or 9 inch) is a drop in fit and will give you the desired 4½ inch bolt pattern. Supposedly the 64-66 Rusclangs had the same spring perch spacing. The I-6s had 4 bolt axles. I don't know if they can be re-drilled. Gears for the 8 inch are harder to find than the Mopar 8 3/4. The 9 inch is extremely stout and widely used. No problem finding gears for these things. Avoid the Phord 8.75 like the plague as it is not supported by the company or aftermarket.

Note: Using a Phord rear will require a combination U-joint to mate the Mopar d-shaft to the X rear end. If you change the reach from the rear of the transmission to the U-joint on the differential, there may be driveshaft length issues.
 
thanks! and as far as spring perches, i'll have to move them anyways because i moved the springs inboard on the frame rails so this just might work out pretty good. i don't really plan on putting too much horsepower to it so i think i'll be ok. it's a stock 318 with a 4bbl and maybe later, a mild cam.
 
A pre-'91 Dakota is also a good one to look into.
I do know that the F body rear is similar in width to the '65-'67 B body rear end and the B body 8-3/4 works very well under a Duster.

On all of these the spring perches should be moved inboard.

Mark.
 
I had an F-body rear under my 70 Valiant for about 4 weeks. I installed it and 2 days later bought an 8 3/4. The tires only rubbed once when I took a corner to fast with only 20psi(on the way to air up after racing) and the 8 3/4 in the trunk. If you are going from a 7 1/4 to an 8 3/4 you will need to find shock plates. 7 1/4 has 2 1/2" axle tubes and 8 3/4 has 3".
 
I've got a complete open 8 1/4 drum to drum w/ brake cables and drive shaft here in Denver for $200.
 
7374 said:
same question. i located a 8.25 from an aspen R/T. will this fit on an A-Body. anyone know the width of this?
Click to expand...
All F-body 8.25 specs are 54.340" flange to flange, 44.46" spring perch to perch,
11.69" axle centerline to centerline of rear u-joint. A-body 8.25 is 51.40"
flange to flange, 43.02 perch to perch, same axle to rear u. Hope this helps.
 
ok,
so i picked up a sure grip 8.25 from what we believe to be an Aspen R/T this weekend. what can i look for stamped on the housing somewhere that can tell me a little more about it?
 
Orv Grote said:
All F-body 8.25 specs are 54.340" flange to flange, 44.46" spring perch to perch,
11.69" axle centerline to centerline of rear u-joint. A-body 8.25 is 51.40"
flange to flange, 43.02 perch to perch, same axle to rear u. Hope this helps.
Click to expand...

That a body measurements is wrong. It's from that bad chart floating around the net.
 
Crackedback, please enlighten us with the correct measurements. Thanks
 
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