I just purchased a 2015 GT 5.0 Torsen IRS (on 08/27) from the Parts Farm in Lyons, GA. My plan is to install it in my '65 Mustang FB. It looks like I will need to have a custom frame fabricated and I will most likely use Daze's carriage approach for mounting, I am having an additional set of forward spring clips inside the frame rails for the mounting carriage.  I plan to maintain the existing Ford geometry but am looking at fabricated upper and lower control links to go with the custom frame. The difference in width is significant between the '65 and the '15 (about 7") this will require custom 1/2 shafts to make this fit. I am having mini tubs installed and the MTF full frame C-6 front suspension.  Paul, 1965 Mustang FB, Woodstock, GA
 

This is a copied post from Stangnet for a S550 IRS cradle. The company is Techno Engines out of Moscow, Russia. 

Hi! We have developed a new irs for the mustang. It is based on s550 components. improved geometry with adjustable toe link. It will be great to work on the track and comfortable on the road. For installation will require a modification of the body, similar to the installation heids IRS. We use energysuspension bushing for easy replacement if necessary. The subframe is assembled from seamless pipes by tig welding. Everything is modeled in the CAD and FEA analyzed to achieve maximum strength with minimum weight. A lot of work has been done and this allows us to get better controllability than when using other solutions. We have just started production and I am looking for people who will be interested in our IRS. We can complete the system for any wheel diameter and used coilovers. If you are interested in this, you can ask me your questions and I will provide you with additional information.  
This was posted on the Stangnet Forum. These folks are located in Moscow, Russia and say they can build you the frame for $5000 and a month fab time. They are involved in the Russian Restomod activities.They can be contacted at  technoengines@gmail.com. Their company name is TechnoEngines. I like the look of their product, but I am not crazy about doing business with Russia.
 

Last edited by Paul65FBProject (2/07/2020 4:25 am)

I found a local fabricator that has been a great help. The IRS support cage, QA-1 coil over shocks, upper and lower control arms are all fabricated and installed. The 8.8" Torsen differential to be installed soon.