1973 mustang rear end swap

jnywadd

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Oct 12, 2018
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I have a 1973 mustang coupe with the stock 8 inch rear that my son and I want to convert to a 9 inch, is their a vehicle's rear and brake system that will work for this? I'm looking for a decent swap but do not want to pay for all new because the car is not going to the dragstrip, just a street cruiser
 
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08GT500

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Jul 12, 2018
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Another possibility, Have you considered going to a Foxbody Mustang 8.8” Rear? Plentiful, Strong, Posi, all the Parts you need- and very economical. I do get it (wanting a 9”), if it’s a Nostalgia thing
 

WORTH

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Is there a problem with the 8", or are you just looking for a stouter rear? Any brake setup on a 9" will work with your stang, as for the 9" there are basically 2 different chucks, a 28 spline and a 31 spline, you can use either. Then the only important thing is the width, measure yours then hit the junk yards. In most cases you can be a couple of inches off and offset it with a wheel spacer or a different offset wheel. Spring purches might be different, but they are easy to move. If you try to piece one together new they get pretty pricey.
 

jnywadd

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Oct 12, 2018
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palm bay florida
Is there a problem with the 8", or are you just looking for a stouter rear? Any brake setup on a 9" will work with your stang, as for the 9" there are basically 2 different chucks, a 28 spline and a 31 spline, you can use either. Then the only important thing is the width, measure yours then hit the junk yards. In most cases you can be a couple of inches off and offset it with a wheel spacer or a different offset wheel. Spring purches might be different, but they are easy to move. If you try to piece one together new they get pretty pricey.
Is there a problem with the 8", or are you just looking for a stouter rear? Any brake setup on a 9" will work with your stang, as for the 9" there are basically 2 different chucks, a 28 spline and a 31 spline, you can use either. Then the only important thing is the width, measure yours then hit the junk yards. In most cases you can be a couple of inches off and offset it with a wheel spacer or a different offset wheel. Spring purches might be different, but they are easy to move. If you try to piece one together new they get pretty pricey.
No, the 8 inch is fine for now, just has an "open end" and due to the fact that we muscled this car up a bit one wheel always spins when you hammer it. The only thing we didn't change in this car is the rear (just the fluids) and I'm afraid it would give under the stress being 45 years old. I could be wrong because I was just going to buy a "lock up" for it and just roll with it. Kinda don't know what to do at this point
 

jnywadd

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Oct 12, 2018
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palm bay florida
Another possibility, Have you considered going to a Foxbody Mustang 8.8” Rear? Plentiful, Strong, Posi, all the Parts you need- and very economical. I do get it (wanting a 9”), if it’s a Nostalgia thing
It everything fits I would definitely do that, its just a cruising car that's a weekend warrior with the new engine and other high performance parts
 

08GT500

Active Member
Jul 12, 2018
767
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Massachusetts
If you do want to go with the 8.8, as ‘Worth’ mentioned, you’ll need to verify Width (there are a few Mustang 8.8’s that run pretty close (-2”) to a 73’) which have to do is zip off the coil-spring brackets, weld on leaf-spring mounts, and perhaps add a different pinion snout, and you’re ready to go with an inexpensive yet strong rear-axle assembly. It will never get any easier or cheaper than this.https://www.powerperformancenews.co...ford-8-8-axle-for-any-leaf-spring-muscle-car/
 

WORTH

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Nov 18, 2002
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Just a note, don't know your son, but putting posi in a Mustang will make them 180 pretty easily if your a beginner or just not mechanically inclined. Or say he's a "bullet proof teenager".

All 3 of my sons hit trees, fences, and signs early on. But "It wasn't their fault".
 
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