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Discussion Starter #1
I can't seem to find a Yes or No on this.

I have a set of 3.55's with a Trac Loc out of a Mustang with an 8.8, will they work in an 97 Tbird with an 8.8?

I called Jegs they told me yes, I looked it up online and it told me yes, I looked it up on here some say yes, some say no.

Help needed....
 

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I know sometimes the number of splines changes in each application, I believe my F-150 8.8" 3.55 Trac loc is 31 spline, but the one in my Mustang is 28 spline...
 

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Discussion Starter #4
"The MN12 8.8 and 7.5 differentials use a 28-spline shaft. The difference between the standard solid axle and the IRS differential is a "Step" (grove) in both differential side gears in order to retain the Circlip (C clip) that holds the Halfshafts in place"

So my question is now, could I take the both differential side gears and swap them for the ones in my car now and make this work?
 

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"The MN12 8.8 and 7.5 differentials use a 28-spline shaft. The difference between the standard solid axle and the IRS differential is a "Step" (grove) in both differential side gears in order to retain the Circlip (C clip) that holds the Halfshafts in place"

So my question is now, could I take the both differential side gears and swap them for the ones in my car now and make this work?
hmm, makes sense. I aint never done it though...
 

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The 8.8s will swap back and forth between ford setups. There's no difference between any Ford 8.8 gears of a given ratio that I know of.. it's just a ring and pinion. The difference comes in the side gears. Solid axles are retained via a C clip. Our half shafts are retained at the hub. The pumpkin side slides and "snaps" in. The reason the IRS gears have a bevel cut into them is so that with a little bit of prying pressure, you can pop them back out. Solid axle side gears have a step groove cut into them to retain a C-clip that holds solid axles in the housing. The pumpkin side of the half shaft will go in and pop into place.. but you'll have a heckavu time trying to get it back out... more than likely, you would have to pull the rear cover to get the half shafts back out. The side gears, I believe, are interchangeable between same type differentials, swap the step-groove side gears for the IRS gears in a traclok. I'm not sure on if they're the same from open to traclok differnential.
 

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The 8.8s will swap back and forth between ford setups. There's no difference between any Ford 8.8 gears of a given ratio that I know of.. it's just a ring and pinion.
Ford Racing FRPP ring and pinon are not the same quality as Ford Factory OEM.
 

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There is a difference between 8.8 FRONT diffs and 8.8 REAR diffs. The ring & pinions are NOT interchangeable. Factory Ford or FRPP gears are generally accepted as being best quality and easiest to set up. Everyone has their own opinion, though.
 

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"The MN12 8.8 and 7.5 differentials use a 28-spline shaft. The difference between the standard solid axle and the IRS differential is a "Step" (grove) in both differential side gears in order to retain the Circlip (C clip) that holds the Halfshafts in place"

So my question is now, could I take the both differential side gears and swap them for the ones in my car now and make this work?
No you can't. The side gears for a trak-lok unit are not interchangable with the side gears for an open rear. You need to either modify the solid axle side gears or get a trak-lok unit for an IRS car.
 
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