SPF Axles??

[Randall Thomas]

Rick Mark IV is correct. And while any of the factory differential offerings can be made to fit in any of the Superformance cars, it does not come without significant modification and fabrication. And frankly the performance and reliability history of all their differentials doesn't make one stand out better than the other, and not enough to warrant a swap.

Superformance makes periodic changes to not only upgrade their cars to the latest technology, but also to keep their major components "relevant" so decades later replacement parts can still be readily available for their owners through the aftermarket. Their history of differential selections also follow this same business model.

Some of the first Superformance Mk-III's in the early double digit cars back in 1993-94 came with straight axle 9" rears and later the Jag IRS. Then again, some also came with 351 Clevelands too. They were just getting started and they had no idea of how big they would become.

Example of a early Superformance car #11...
Superformance Owners Forum's SUPERFORMANCE NEWS

Once making "production" cars they went to the cast iron 8.8 IRS from the 1989+ T-birds with 3.73 gears, however the T-bird differentials were not easy to get and to stay relevant, Superformance used the same 28 spline differential found in the T-Bird's cousin, the Lincoln Mark 8. However, those were aluminum cased differentials and these came in the mid 200-300 series Mk-III's starting in 1998. In addition around car 300 the differential was raised to provide additional CV clearance and in 2000 around car 900 the upper mount brackets were reinforced to handle the increased power plants the owners were now using, some up into the 1,000 hp mark. And more.

Ford 8.8 Iron and Alum diffs...
http://superformance.org/differentials/Ford_8-8diff.jpg

Since the 8.8's in the Mark 8 were long out of production since 1998, to stay relevant once again at car 2069 Superformance decided to use the Australian sourced Dana 7.75" B.T.R. found in the 04-06 American GTO as well as the Aussie Holden cars. The gear ratio was 3.46 and this would be December 15, 2004. As a side note the Superformance/Shelby lawsuits were settled on February 5, 2005 where Superformance cars were licensed by Carroll Shelby to be built under his licensing and Superformance was now building the CSX cars for Shelby.

Dana BTR diff...
http://superformance.org/differentia..._7-75diffR.jpg

The Pontiac GTO did not last long in production, for about 2 years and soon after Pontiac itself was defunct by October 31, 2010. So to stay relevant once again Superformance looked for the most recent and equally robust offering which was the ZF rear differential found in the 2010 Camaros. This had a 3.45 ratio and was first installed into cars in the mid to late 2900 series around the beginning of 2010. These were physically large differentials to fit under the car and created a little more driveshaft misalignment which required some chassis modifications at car 2996 to improve those angles.

The photo below is the prototype ZF differential I personally took at the Factory in South Africa in February of 2010. Once viewing the photo, if you click "next" you will see a series of photos of the diff as well as mounted in the car with the axles it uses...
1567mon_hitech_zf_differential1

And once again to not only stay relevant but also take advantage of the latest technology, in car 3315 Superformance began using the new Ford "Super 8.8" cast iron differential found in the 2015-16 Mustangs with a 3.55 gear ratio. This new 8.8 is nothing like the previous older 8.8 unit and will not fit in the older cars with the Mk-8 8.8 differential without significant modifications.

Ford "super 8.8" diff...
http://superformance.org/differentia...per8-8diff.jpg