03 Cobra IRS ??

I dont know about your yoke but you will need to strech your stock gt rear brake lines the cobra lines did not match up to my 99 gt vert or get different ones

the lines would not thread for me I think you will need some different fittings. I need to look back into it for my car. Love the way it drives now with the irs

Change this
03-04 Mustang Cobra Pinion Flange by Ford Racing at LRS - Same Day Shipping!

to this
86-04 Mustang 8.8" Rear Pinion Flange by Ford at LRS - Same Day Shipping!


But why? What is different?

different thread or something. I am going to look back into it soon but for now out of money. House payment first so for right now the car is parked.

The flanges all seem to match any set of 8.8 pinion splines. cobra to gt / gt to cobra. the difference is in the driveshaft flange mounting holes to pinion flange hole pattern. the cobras pattern is slightly larger than the GT's. So long story short. my 04 cobra is getting a gt rear put in within the next few weeks and i will reuse my stock aluminum driveshaft and i will remove the pinion flange from the IRS put a new pinion seal in the straight axle and install Cobra flange to GT straight axle. I will put GT rubber brake lines in place of the longer Cobra lines on the drop down from the body, and use the smaller GT rotors with the Cobra calipers. Without the 98 cobra/03-04 mach caliper mounting bracket the larger Cobra/mach rotors wont fit. The above mentioned brackets are the only difference to utilize the larger rotors. The rear calipers,brake pads are the same. Basically the mounting bracket is larger from axle mount point to caliper mounting point. that is the only difference that I know of from those desired rear ends to the standard GT rear's. Notes: GT rear brakes work fine for street use on Cobras. The 99-04 GT rear axle is a little over 1 inch wider than the previous platforms axle. Shocks, springs, catback exhaust for straight axles need to be with straight axles and Vice Versa for IRS. I just order lowering springs, spring isolators, and catback exhaust for 99-04 GT. Front and rear will interchange with this swap but order your springs based on GT ride height not cobras slightly lower stance.

Hope this helps, Art

jtm604 said:

I finally got around to it last week and finished it Saturday. I got a cobra yoke and a 448 u-joint to do the swap and everything is fine. Now of course the ass is to high and needs lowering springs to make it level again. The big issue for me is getting it aligned. The shops by me are stupid and I'm thinking I need to tell them it's an 03 cobra cuz there gonna scratch there heads when I say a 99 gt with a 03 cobra irs.

Click to expand...

Exactly!