Article - Install a 4R70W into a Cobra

Driveshaft spacer for 03-04 rear pinion flange!!

Bump to an old thread to add some usable info!

Hello everyone. It has been years since I have been on here and much appriate the info on the 4r70w swap since I am in the middle of a swap on my wife's 03 vert. We picked it up 2 years ago now and I have been the only driver since my wife has not picked up learning to drive a stick besides around a parking lot. So now I am putting a 4r75w in it for her. This one is a cruiser that I resurected from the grave and my turbo 03 Cobra is the race car so it is all good. Lol

I always like adding my findings back into the pool after finding better options to make things even easier.

I wanted to share some info for others that might be in this boat and hope the artical can be updated with my findings. I found there is no need to by the steeda driveshaft spacer and convert the DS and rear flange to the GT size. The rear flange factory on the Cobras are the same 3 inch bolt hole to bolt hole unit (with a 2 inch centering hole) used on the F150s and we all know there are a ton of companies making lift kits for them and in turn driveshaft spacers. What you need is a FABTECH FTS92003 Drive Line Spacer it is 3/4 and comes with bolts (I will verify if the bolts are correct later). The spacer is a direct bolt up to the rear of the 03-04 cobra driveshaft. :rock: That was step one!! Next I ordered a slip yoke for the the front that fits the factory driveshaft 1350 size but is almost 7 inches from the center of the hole to the end of the splined slipe yoke. This should add another half inch in length to take the 43 inch cobra driveshaft to the needed 44.5 inch length for the 4r70w and 4r75w transmission with the factory IRS. My goal was 45 inch but thats close enough in my book and much better than just running the steeda spacer with all the down graded GT parts to make it work. I will list the part numbers and pics when the part is here and I get to test fit it but according to my measurments it will give more spline engagment and allow people doing this swap to used the factory 03-04 cobra driveshaft with proper spline engagment.

I hope this helps because I put a ton or research into this. I just couldnt bring myself to buy a custom 45inch drive shaft when the cobra unit is so nice from the factory. The spacer was $45.50 and the slipyoke was $79 if I remember correctly and everything should fit perfect. Stay tuned as I work on this project for my wife.

Project notes:
Rebuilt 19k mile 03 Cobra vert
TVS superchager and all supporting mods
4r75w transmission with GT converter (Mach1 would have been better stall from my reading but very close)
HGM Compushift Sport transmission controller (Wife wants it to drive like the 2004 GT factory auto that we sold.)
Derale 20561 transmission cooler in front drivers side fender. (only slite mods to bracket and one hole in the car's metal to mount it)
All the misc auto swa parts are out of a wrecked 2004 GT. gear selector, pedal, cables and so on. Got it all. Lol