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Discussion Starter #1
Is the MN12 supercoupes and xr7's the only ones that had the trac-loc pumpkins in them??

I've got a line on a SUPER cheap 99 cobra IRS rearend but the pumpkin is cracked along the bearing retainer so I'll need another pumpkin.

I figured while I'm at it, I might as well get a trac-loc unit from the u-pull and keep the 28 spline diff for another project...

they are all iron too arent they?? any vehicles aside from the cobra that came with an aluminum center??

not that it concerns me, I'm sure the iron one has to be a little stouter than the aluminum units and it cant weigh more than 25lb than the aluminum one which doesnt really bother me.
 

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To my knowledge, all Mark VIII's differentials are Aluminum, but NONE have trac-loc's in them.

The Cobra IRS should be a trac-loc and all you should need to do is rebuild it (w/ extra clutch pack and F150 spring) after planting it into another case (steel or aluminum).

But just my .02. :thumbsup:
 

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My 96 LX has a 3:27 Trac-loc from the factory :)
 

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Motorboatin' SOB, Headlight Cleaning Guru
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the 94/5 sc pumpkins came with traction control, i believe. not trac lok. some v8 mn12's came with trac lok i think. you need to look for the letter "e" under the ax code on the driver side door jamb sticker. that denotes a 3.27 trac lok pumpkin.
 

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Discussion Starter #5
To my knowledge, all Mark VIII's differentials are Aluminum, but NONE have trac-loc's in them.

The Cobra IRS should be a trac-loc and all you should need to do is rebuild it (w/ extra clutch pack and F150 spring) after planting it into another case (steel or aluminum).

But just my .02. :thumbsup:
hmm forgot about the mark VIII's...

as for the differential itself. I've already had a look at it and the damage went through to the diff itself and cracked it right on the outer left bearing assembly.

I was just going to pull a locker from a v8 explorer or mountaineer and use that with the ring/pinion from cobra diff.

only thing is I was trying to figure out my best bet for a new housing. I know there's two mark VIII's out in the yard now so hopefully they still have the housing in them. :confused:
 

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Motorboatin' SOB, Headlight Cleaning Guru
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im parting out a mark viii. complete pumpkin is still there.
 

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if you get an explorer carrier you will need the right side gears as they are 31 spline
 

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...and you want the side gears with the bevel for use in the IRS, or you will be cussing when you can't get the axle out of it.

That reminds me, I need to get DirtyD0gs mailing information and get my side gears sent to him so he can machine them, no one locally wants to even think about doing it.

Any recent 8.8 Trac-loc will have the beveled side gears, I should just get a new one instead but I can't justify the expense, even though it will make my left side tire last longer :)
 

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...and you want the side gears with the bevel for use in the IRS, or you will be cussing when you can't get the axle out of it.

That reminds me, I need to get DirtyD0gs mailing information and get my side gears sent to him so he can machine them, no one locally wants to even think about doing it.

Any recent 8.8 Trac-loc will have the beveled side gears, I should just get a new one instead but I can't justify the expense, even though it will make my left side tire last longer :)
How much are the new ones going for now?
 

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Discussion Starter #10
...and you want the side gears with the bevel for use in the IRS, or you will be cussing when you can't get the axle out of it.

That reminds me, I need to get DirtyD0gs mailing information and get my side gears sent to him so he can machine them, no one locally wants to even think about doing it.

Any recent 8.8 Trac-loc will have the beveled side gears, I should just get a new one instead but I can't justify the expense, even though it will make my left side tire last longer :)
side gears?? you mean the side spiders??

explorers are already 31 spline units. I guess I could re-use the gears in the cobra diff since its only the case on the diff itself that took damage...looks like all the internals in the diff itself (not talking about the overall aluminum case) are ok.

still trying to figure if $250 is a good price or not for this thing. Just trying to weigh all the legwork I'll have to do versus actually getting it for so cheap lol.
 

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IMHO, $250 for a cracked case Cobra IRS rear end is too high. Mark VIII rear ends are much cheaper, then all you need to find is a used, 28 spline trac-loc unit (preferably with the later style gears that are machined for the IRS, or buy new ones), and rebuild it (which you will have to do anyway if you are swapping the internals from the Cobra to another case.) And I would bet the clutch packs are toast in the Cobra differential.

$250 for a (most likely worn out) trac-loc and some, what 3.27 gears, from a known bad case? :beek:

Just my opinion though. :thumbsup:
 

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Discussion Starter #12
well mainly considering I want it for a mustang, its not "that" bad since the cobra unit is the only IRS I can really use. I was going to offer him $200 as it is anyway since it's complete with everything I need except for the cobra specific exhaust.

normally they sell for around $800+ with the $800 units being the IRS itself only.

but yeah, considering I've gotta go through the entire center section I dont really wanna pay the $250 for it.

but at least doing that I can do whatever I want to it inside such as adding a few more clutch discs to the new unit as well as change the gears, etc.
 

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I bought my Mark alum rear for $40, brand new trac loc from gefracing.com for $159 and in turn have myself a '99 Cobra rear. They are just high because its Cobra parts and Cobra guys will pay that for them.

Also the prices on the gefracing website are higher than what they really are. Just call them they are really reasonable. I think they are top 5 in the country on volume of selling FRPP so they can sell cheaper.

Clint Hill
 

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Discussion Starter #14
I bought my Mark alum rear for $40, brand new trac loc from gefracing.com for $159 and in turn have myself a '99 Cobra rear. They are just high because its Cobra parts and Cobra guys will pay that for them.

Also the prices on the gefracing website are higher than what they really are. Just call them they are really reasonable. I think they are top 5 in the country on volume of selling FRPP so they can sell cheaper.

Clint Hill
no, what I meant was the entire IRS unit with subframe assembly. the cobra unit is the only one that is a physical bolt-in to the foxbody and sn95 mustangs. If I could get a markVIII IRS with subframe or mn12 tbird unit, etc to bolt straight into my 86 svo I'd have already grabbed one from the u-pull for $100 and swapped in the explorer parts there in the yard to get away with highway robbery haha.
 

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Yeah, I think you were a little too vague in what you are really after and doing.
 

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Discussion Starter #17
Yeah, I think you were a little too vague in what you are really after and doing.

yeah, my bad, just figured everyone knew...until I remembered that this is a tbird site and most of them already have IRS lol.

anyway, here's the actual damage I'm looking at on the center section. after getting there and opening it, it was all bad. but still price is pretty decent.

you can actually see how it is cracked bad enough that the cv axle is crooked. somebody got rev happy at a stoplight haha.

 

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until I remembered that this is a tbird site and most of them already have IRS lol.
i think we all have irs ;) except for anything '88 and older.

that's some carnage right there. i have heard of axles breaking but never the case.
 
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