Quick question.... one of my buddies has a t-bird supercoupe that he has a spare rear center section with a rebuilt posi in it- would this bolt directly into my mark?? ive heard that they do but i just wanted to make sure (i was thinkin of puttin 3.73s in it and finally puttin down some posi rubber) thanks for any help!
-jeff

You should be able to swap the differential housings, only difference between the T-Bird SC housing and the mark 8 is the Bird housing is cast and the mark housing is aluminum. I would suggest rebuilding your housing with the SC gears and posi.

Yes, as long as it is one of the newer years with the 8.8 IRS. You will also need a speedometer gear and you should seriously consider a new drive shaft. It's also helpful to get a tune for shift points.

yes, but the bird is cast and the mark is aluminum. midwestbird is planning on puttin the pumpkin and lower control arms into his bird to save weight

yea ive got an sct xcal2 so you can change the ratio through that which adjusts shift points, speedo, etc. I would def do a mmx driveshaft too. One more thing- what is the diff between trac-lock and posi? or is this the same thing just two different terms for it?

yea ive got an sct xcal2 so you can change the ratio through that which adjusts shift points, speedo, etc. I would def do a mmx driveshaft too. One more thing- what is the diff between trac-lock and posi? or is this the same thing just two different terms for it?


It is NOT a locker but is a limited slip Ford's Name. POSI is actually GM's name for it. The wheel releases when going around corners to prevent the outer wheel that is of course turning more than the inside wheel from hoping and skipping. With a LOCKER both wheels are locked together at all times, although there are soft lockers that release when going around corners to be more streetable. Here is a link that may help you undersatnd even better.

http://auto.howstuffworks.com/differential.htm

i understand the difference between limited slip and locker- i had a locker in my 66 stang for a while and boy that was scary around corners... i had just never heard of limited slip referred to as trak-loc.... kinda weird cause i worked in a ford dealer too, guess we all had GM on the mind... thanks for answering the question tho!

Trac-lock is not a "locker" but it is posi.


Trac-lock is fords name for it just as you said.

And I'll second or third or whatever that a SC 8.8 IRS pumpkin is a direct bolt-in.. .