8 1/4 rear question

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Wizard

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Will a 8 1/4 rear fit in a 71 duster or did they come stock with them? Have a 7 1/4 in it now but want to go to big bolt pattern. What are my options? Can u change out axles? Have to go to the 8 3/4 rear? Would like to just put in a 8 1/4 in it? What is length of it drum to drum?
 
Wizard said:
Will a 8 1/4 rear fit in a 71 duster or did they come stock with them? Have a 7 1/4 in it now but want to go to big bolt pattern. What are my options? Can u change out axles? Have to go to the 8 3/4 rear? Would like to just put in a 8 1/4 in it? What is length of it drum to drum?
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If it came out of an a body the whole entire rear end should be more than less a direct swap.. most internal parts are not interchangeable between different size rear ends. You can probably get away with brakes and Brake plates..
 
j par said:
If it came out of an a body the whole entire rear end should be more than less a direct swap.. most internal parts are not interchangeable between different size rear ends. You can probably get away with brakes and Brake plates..
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Did they have 8 1/4 rears in dusters? for a 318 or did they still use 7 1/4 stock for 318 and slant 6?
 
Wizard said:
Did they have 8 1/4 rears in dusters? for a 318 or did they still use 7 1/4 stock for 318 and slant 6?
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I'm pretty sure they made it in the quarters for the later model years of a body's. Those other questions concerning whether they had a 318 or slant 6 you'll have to wait for somebody else to chime in who knows more...
 
Wizard said:
Did they have 8 1/4 rears in dusters? for a 318 or did they still use 7 1/4 stock for 318 and slant 6?
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8.25 can be found in any A-body 73-76. Some would be obvious like a '73 340 or any 360 car. But for no rime or reason, they can come in a slant car also. Your drive shaft will need to be shortened. Also, you'll need different shock mounts or drill the ones you have. 8.75 rear ends could be found in A-bodies 72 and older. Just another option would be 8.75 B-body rear end from '65-70 years. Plenty available and usually cheap.
 
I looked going to a 8&1/4" and was unhappy with the gearing choices. And with 8&3/4" I was unhappy with the cost. I bought a 1965 mustang 8" rear for ~$200 that I plan to install this winter. The perch spacing and hub spacing are almost identical to my 1965 Valiant (I think your Duster has the same spacing as my 65 Valiant.). Someone sells and adapter u-joint. (I forget who.) The Ford axle Has the 4.5" bolt-pattern. Has 3.00 gearing. Has 10" drums though... so I am only planning to upgrade once I get the front discs breaks in (I don't want the rear to have bigger brakes than the front). That project should start in a month or something. Going to big-bolt pattern to have more wheel options. Anyway... FWIW, I really haven't started the install so there are probably some unknown unknowns. (Like: do I have to shorten the drive-shaft and what to use for a pinion snubber.) Anyway, the old Mustang rears could be an option for you... if you are not 'anti-Ford';-)
 
The "best" swap is the 65-67 B body 8 3/4.
(68-70 are wider)
Almost every 66 B body had one and a whole bunch of 67's did.

The "next best" is probably an F/M/J body 8 1/4.

Those are the non-A body axles with closest to A body measurements.
 
YY1 said:
The "best" swap is the 65-67 B body 8 3/4.
(68-70 are wider)
Almost every 66 B body had one and a whole bunch of 67's did.

The "next best" is probably an F/M/J body 8 1/4.

Those are the non-A body axles with closest to A body measurements.
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appreciate all the thoughts. Keep them coming but do like the 65-67 b body swap so far.
 
Wizard said:
appreciate all the thoughts. Keep them coming but do like the 65-67 b body swap so far.
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Did this swap before, and just did it again in my '76 Duster this summer. I have another one I'm getting ready to put in my '74 Duster. 65-67 are the best for A-bodies, but the 68-70 are just about the same width.
 
318willrun said:
Did this swap before, and just did it again in my '76 Duster this summer. I have another one I'm getting ready to put in my '74 Duster. 65-67 are the best for A-bodies, but the 68-70 are just about the same width.
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The 65-67 just bolt right in? With springs from b body or u use the A body springs?
 
Wizard said:
The 65-67 just bolt right in? With springs from b body or u use the A body springs?
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perches are a little wider on the b-body. some weld new perches, some just spread the springs, some oval the spring perch holes on the b-body rear end and spread the springs just a tad. This last is my preferred way
 
Another option if you want a lower gear, 87-90 dodge dakota will fit, and most comes with a 355 or 391 gear on the 4x4, you would have to move spring perches to bottom of housing, or if you find a 2wd, their perches are mounted on bottom already, just need to verify gear ratio, it adds about 1 inch on each side ,which with a duster, there is plenty of fender space, and it also will let you use a wheel with more back spacing without the tires rubbing the leaf springs
 
318willrun said:
perches are a little wider on the b-body. some weld new perches, some just spread the springs, some oval the spring perch holes on the b-body rear end and spread the springs just a tad. This last is my preferred way
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Yup this is what I will do since I have a 8 3/4 out of a 70 charger........that made me cry she was too far gone! She only cost $100 tho.
 
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