Got the Bastered Rear

Not ALL of them. The real late ones got the 8" axle.

 

I would love to put my spare MKVIII IRS in my 73 Mav, but alas I cant find a way. YET

 

No lie... In los Angeles they go quick. I bought and used a 8" 65 Fairlane then found the spring perches were wrong. 66 and up is the ticket for perch location. (Hard learned info there...)

 

My dad just got a Tbird the other day, and I started looking for that rear sub frame immediately

I was planning on doing the swap to my old one, but alas I sold it.

 

Ive put them in 57s damn smooth, got the idea from a friend who put one in a 50 Mrec and another in a 57 pick up shock waves and coil overs. The problem with the mav is the width. Ive modified the cradle on the MKIII to fit a 57 the width is perfect. The mav is another hurdle. Ill get to it some day.

 

yeah, i figured there might be a handful of really late '70 models that might have gotten the changeover but for the most part theyre 8". one of my '70 2dr's that i parted out was built 6/70 and still had the 7.5" in it

 

You would have more options then you think.
The FN10 and MN12 share the same rear setup except the FN10 is air ride, has aluminum diff housing and lower controll arms, but they interchange back and forth.

So you have 93-97 MarkVIII
89-97 Cougar and Thunderbird (watch out for the 7.5 rear)

The SC's and XR7's had limited slip 8.8 and all the cars with ABS came with a 8.8

The easier swap would be the 99 Cobra IRS. It's a nice neat package.

 

I fixed your thread in the quote above.

I have seen as early as May of 1970 with an 8".

 

Those 7.5" rear ends must have been pretty weak. When I was 16, I slid off the road in the rain (rock hard Uniroyals....they may have been the original tires) and thru a ditch in my Maverick. I didn't think it hurt anything but soon found both rear axles were bent and the wheels were wobbling. That was when I had to put an 8" in.

The 8" I used was out of a 67-68 Mustang. It was wider but worked well with the 69 Mach 1 wheels. I'd imagine a 67-68 Mustang rear end would be the ticket if you plan on running late model Mustang wheels. That way you wouldn't need spacers in the rear.

Now I have the correct Maverick 8" in my car and it is an obvious difference in width. So much so that the Mach 1 wheels didn't look right. I changed to 15" Torq Thrusts to fill the wheel housings a little better.

 

My spare is an FN10 same as the one I put in the 57. Thanks Bro Im gonna keep my eyes open for the 99 Cobra IRS