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1996 Thunderbird LX
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253 Posts
Discussion Starter · #1 · (Edited)
I am getting conflicting information all over the place so I thought I would ask here. My pumpkin says 8.8 in the casting and is aluminum. I also have rear disk brakes. But when I jacked the rear of the car up and turn the wheels they spin in opposite directions. When I drive it I can easily induce a drift.

Here is the codes:
41692

Maybe you guys can tell me a little bit more about my car in the mean time if you want.
 

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1991 Mercury Cougar LS 5.0 in restoration
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903 Posts
It's 3.27 trac-loc.
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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Here is the article on gears and axle codes.


If it's an aluminum pumpkin on an MN12 it's not factory, and the axle code on the door jamb sticker means little at that point. One thing to keep in mind though is the rear cover is aluminum for aluminum and iron pumpkins alike, so to be sure, check whether the rest of the housing is aluminum or iron.

If it is aluminum, it's possible someone swapped in an aluminum pumpkin from an FN10 which will have either a 3.07 or 3.27 open. Given your observation that the wheels spin in opposite directions it's an open diff (or the trac-loc clutches are completely shot).
 

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1996 Thunderbird LX
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253 Posts
Discussion Starter · #4 ·
I could have just looked at the cover. Thanks for all that info. Is a rebuild of these simple if it does end up being trac-loc?
 

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I could have just looked at the cover. Thanks for all that info. Is a rebuild of these simple if it does end up being trac-loc?
The worst part is the smell. :)

You will want to drain it carefully. :)

I took one apart 5 years ago, and I can still smell it in the garage. :)
 

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1996 Thunderbird LX
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253 Posts
Discussion Starter · #7 ·
The pumpkin is iron so it is a trac-lok! After I get the car running I will rebuild the diff. This is so freaking cool!
 

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The only cars with an aluminum Case were marks; no marks had locking diffs. Not all iron diffs are locking. look at the tag. an L means locking. 3L27 is locking.
 
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The Parts Guy
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7,727 Posts
The New Edge Cobra's and the FRPP diff cases were aluminum as well. Those units did come with LSD's, but only the '99 or the FRPP unit would be a drop in for a MN12.
 

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The New Edge Cobra's and the FRPP diff cases were aluminum as well. Those units did come with LSD's, but only the '99 or the FRPP unit would be a drop in for a MN12.
I got one of those FRPP pumpkins when they were available many years ago. Aluminum w/trac-lock and 3.73 gears
 

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The Parts Guy
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I got one of those FRPP pumpkins when they were available many years ago. Aluminum w/trac-lock and 3.73 gears
When they were available, they were a good deal and an easy way to jump to 3.73's with a Traction-Lok. I've had three of them; sold one with a car, sold another to Chris Wise with my 35th Anny, and I still have one on my shelf.
 

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When they were available, they were a good deal and an easy way to jump to 3.73's with a Traction-Lok. I've had three of them; sold one with a car, sold another to Chris Wise with my 35th Anny, and I still have one on my shelf.
Like so many things with these cars back in the day, get them while you can.
The FRPP pumpkin, the Dynotech MMS driveshaft, the DirtyDog convertor and the PI Motor with the Jerry Tune and JMod makes for one hell of a sleeper daily driver. Add the JL chassis really stiffens the Unibody. I really like slaying the 1500 Ram Hemi trucks, they think they are so bad.
 

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The Parts Guy
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I have a sinking feeling this is open....
You can't make any determination from that photo other than the fact that it's a 8.8".
 

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1996 Thunderbird LX
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253 Posts
Discussion Starter · #15 ·
I guess I will just stop farting around and take the cover off when I get back home.
 

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1991 Mercury Cougar LS 5.0 in restoration
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If there is no indication that is been changed, the tag does state it's TL. I wouldn't open it up unless I had a rebuild kit ready to go. The stink is not worth doing it twice
 

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Unless the TL is burned out, it should take about 10 seconds of spirited driving to feel if it has one.
 
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