I am planning on installing IRS into my old 49 F1. I've read a few threads on here where the VIII was used as well as T Bird and Cougar IFS .I have a 1989 Lincon VII here I would like to use. Can anyone tell me if the IRS from a 89 Mark VII is the same as the one in the VIII. I can get the VII for the install but just want to make sure the dimensions are close to the same. I will be going with the Jag XJ6 IFS.

 

Hello,
I can't comment on the Mark VII but I just completed installing the
Mark VIII IRS in my 50 merc. I bought the kit from Team 321 and the install is straight forward and fairly easy if you can weld. I do know that the Mark VIII is an MN12 chassis and will be different than the Mark VII.
I am very pleased so far on how the rear fit with this kit.
I will try and post some pics later today.

Drew

 

48 steele has a ford irs in his F1, Tbird IIRC. Jag front end also. Send him a PM, or he may be on here soon with your info.

 

Thanks but it turns out to be someones feeble attempt at installing an IRS from a newer doner vehicle into their old mark vii. I jacked it up out of the snow and crawled under it. Some one had tried using angle iron and tubing to try and fit it under the mark vii. Now I know why we had to trailer it home when we bought it. Needed the motor for the Jeep but then went to the sbc instead.

 

So now I start over. I've researched the alot of the threads looking for info on putting the IRS into my 49 and the 1 thing that seems to be missing is what year vehicles are acceptable doners. I know the 93 - 97 Mark III works quite well but how about the T birds or the Cougar. Can someone tell me the years that will work for these cars and any other doners that would work as well if you know of any.

 

The person you need to contact is Dave Held. I am sure he will have your answer. His email is: dheld@cfl.rr.com
His company, 321 IRS makes the install hardware for the IRS's.

__________________________________________________ ____
46 Ford Tudor - Street Rod
48 Ford F1 - Darkside

"Happiness- 3 pedals and a 5 speed"

 

Here is what I know about the IRS in the MN12's. 89-93 Thunderbird SC's had the IRS with 8.8" diff and limited slip. Auto's had 3:27 gears Manual had 2:73 gears. I think 94/95 SC's had the same gearing but may have had open diff's. All SC's came with rear disc brakes.
89-97 LX birds had either 8.8 or 7.5 rear end depending on V8 or V6. And some of the early ones may have drums.
93-97 Mark VIII's have the same rear end as the bird only the diff case and lower control arms are aluminum which is a little lighter than the birds steel ones. I believe the Marks diff were open and had 3:08 gears.
Oh yeah, Marks had air bags and the lower control arm is flat on the bottom were as the birds have a hump in the middle to center the spring.
Someone may have more info to add.

Drew

 

[quote=Drewsc;11101517]Here is what I know about the IRS in the MN12's. 89-93 Thunderbird SC's had the IRS with 8.8" diff and limited slip. Auto's had 3:27 gears Manual had 2:73 gears. I think 94/95 SC's had the same gearing but may have had open diff's. All SC's came with rear disc brakes.
89-97 LX birds had either 8.8 or 7.5 rear end depending on V8 or V6. And some of the early ones may have drums.
93-97 Mark VIII's have the same rear end as the bird only the diff case and lower control arms are aluminum which is a little lighter than the birds steel ones. I believe the Marks diff were open and had 3:08 gears.
Oh yeah, Marks had air bags and the lower control arm is flat on the bottom were as the birds have a hump in the middle to center the spring.
Someone may have more info to add.




My 93 Mark VIII has 3:07 and I got the upper and lower spring pads out of a T-bird and installed t-Bird comp springs.

 

Excellent! This is just what I was looking for. Thanks for the info and thanks to Dave who responded to the e mails I sent to his site. That adapter kit makes the install look way easier. I was wondering how long it was going to take me to fab something up. This way I can just build instead of think to hard. 48 Steel, you have some great photos in the gallery and I wonder if you realize how much of a help these really are to those of us who have yet to tackle a project like this. Now I just got to get the truck from the farm and get started. Drew if you get some pics posted let me know. I'd like to check them out. Thanks.

Remi

 

Remi,
Here is a link to some pics I posted today.

Drew
https://www.ford-trucks.com/forums/1...y-50-merc.html