TCCoA Forums banner

1 - 20 of 27 Posts

·
Registered
Joined
·
214 Posts
Discussion Starter #1
If one has a 96/97 TBird and wants to upgrade gears to 3.73 what year/model stock 3.73 pumpkin can be swapped into the bird?

I see a ton of 96+ Explorer rear ends out there for pretty cheap. Would be nice to pick one up and have it rebuilt.

Thank you!
 

·
̇
Joined
·
3,701 Posts
Your answers will vary on what Differential to use..Everybody has their own preference..

Between the Aluminum 8.8 IRS Differential found in the 93-98 Lincoln Mark VIII..To the Iron 8.8 IRS Differential found in all 89-97 Thunderbirds/Cougars..

Just make it easy on yourself, and grab an Iron 8.8 Differential from the junkyard..Make sure to find one with a Trac-Lok already in it..

That will save you some $$$$..

Unless you're rebuilding the Differential yourself (which I don't recommend)..

The cost to have the Aluminum Differential built may be slightly more than that of the Iron since you need a case spreader to install the guts..

Buy some Ford Racing 3.73 gears, and find a shop to put it all together for you..That's what I would do in your shoes..

No 8.8 IRS equipped car ever came stock with 3.73 gears..

Explorer rear ends will not work..You need a rear end from a 93-98 Lincoln Mark VIII or a 89-97 Thunderbird/Cougar..






Rayo..
 

·
Registered
Joined
·
214 Posts
Discussion Starter #3
Since removing the one on my car to have it rebuilt is not an option, what is needed to build a new one from scratch?

Having a hard time finding TBird or Mark VIII pumpkins online.
 

·
Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
Joined
·
9,374 Posts
The only pumpkin you can use is one from an MN12 or FN10. No other cars will "swap". If you can't remove the one from your car to have worked on, you're going to need to find another one from a donor vehicle.
 

·
Registered
Joined
·
2,806 Posts
I have a 3.73 differential for sale. With the '00 trans you bought from me, you would need to use a SpeedCal to get the speedo right though.

-Bryan
 

·
Administrator
Joined
·
8,114 Posts
Do the V6,SC, and V8 all have the same differentials for all years 89-97?
Yes and no. All SC and V8 cars came with an 8.8 and some V6s had them also. Any pumpkin from any year will work, even a 7.5! :)

Joe
 

·
Registered
Joined
·
309 Posts
So some V6's have 7.5 or 8.8. Can I see the difference by looking at it, is one pumpkin bigger and one smaller. Does the 8.8 last longer?
 

·
Registered
Joined
·
4,309 Posts
Unless you're rebuilding the Differential yourself (which I don't recommend)..
Cmon .. they are easy if you have the correct tools. :tongue:


I thought the explorer and mustang rear ends work its just once you put your axles in you will have a hellva time taking them out again.
No Mustang .. not sure about Explorer. The Cobras from 99 and maybe 01, had the 28 spline side gears that will work direct swap. The 03/04 are 31 spline. and need to be machined to match.


So some V6's have 7.5 or 8.8. Can I see the difference by looking at it, is one pumpkin bigger and one smaller. Does the 8.8 last longer?
You have a 7.5. Its stamped on the rear cover. The larger ones are capable of handling more power in the drivetrain.
 

·
Super Moderator
Joined
·
10,772 Posts
So some V6's have 7.5 or 8.8. Can I see the difference by looking at it, is one pumpkin bigger and one smaller. Does the 8.8 last longer?
IIRC, The 8.8 was added to keep from breaking from the added torque from the 4.6l engine. And the SC, of course. Yeah, I know the SC came first. :)

The 8.8 rear cover is more oval, and says 8.8 at about the 4 o'clock position on the back face; you may need to rub dirt, but it's raised in the casting, on the passenger side of the bracket. :)
 

·
̇
Joined
·
3,701 Posts
IIRC, The 8.8 was added to keep from breaking from the added torque from the 4.6l engine. And the SC, of course. Yeah, I know the SC came first. :)
The stock 4.6L in the MN12 has never been known as much of a "torque monster"..

Don't forget the 5.0L MN12 came before the later modular MN12's..and...All 5.0L MN12's got the 8.8 rear end..


Here are the 8.8 and 7.5 side by side, for comparisons sake:
8.8 vs 7.5 Differential.JPG







Rayo..
 

·
Super Moderator
Joined
·
10,772 Posts
Don't forget the 5.0L MN12 came before the later modular MN12's..and...All 5.0L MN12's got the 8.8 rear end..

Rayo..
I have a 7.5 laying here, as a spare, because it was free.
I won't be running it unless I have to; it's not as beefy, regardless of pix. It does have a 3.55, according to the code.

I haven't forgotten anything about a 5.0 pushrod motor at all. :) OHC iz way More Roxors, tho. :tongue:

I seem to remember something about 5.0 engines ripping themselves in half over 500 hp or thereabouts, tho... No, that was my buddy's Mustang, lol
 

·
̇
Joined
·
3,701 Posts
I seem to remember something about 5.0 engines ripping themselves in half over 500 hp or thereabouts
Hmmm..

So what your saying is..As long as I stay at the power levels that you are at in your MN12's..I won't have to worry about that then huh?..

Besides..This thread isn't about how much power a stock Iron MN12 modular block will take before it splits vs its pushrod counterpart.. :rolleyes:

Back on topic.. Swappable rear differentials






Rayo..
 

·
Registered
Joined
·
1,716 Posts
I don't know how the 7.5 and the 8.8 compare in real world torque ratings and such, but I just rebuilt a 7.5 for a Ranger guy and I have to say...... I did a lot of snickering just looking at that ring gear. I couldn't help it! It may or may not have been deserved, but when you're used to doing 8.25, 8.75, 8.8, 9.25, 9.75 rears the 7.5 just looks like a toy. lol
 

·
Super Moderator
Joined
·
10,772 Posts
Hmmm..

So what your saying is..As long as I stay at the power levels that you are at in your MN12's..I won't have to worry about that then huh?..
I do know the fox body my Dad had was a 5.0 with a 7.5, and it wasn't near the car my MN12s are. :D

And I just posted that to annoy you, not 5.0 owners. :wavey:

I can think of two stock power 5.0s that split in half just from passing someone. Must be that monster torque!
My buddy makes that three, lol.

...the 7.5 just looks like a toy. lol
Yeah, that's my impression as well. I keep it as a backup. :)

You never know what you're going to break... :D
 
1 - 20 of 27 Posts
Top