Instead of a ford 9" I picked up the rear independent suspension from a 2015 Camaro SS.
After finding the stock center line, and leveling/measuring everything I braced the rear section with some scrap pieces to keep them in place while I cut the frame to make room for the Camaro IRS.
I think this voided my warranty...
I got the subframe up and level to where ride height was even with the front.
I cut off the stock mounts where the IRS bolted to the Camaro chassis and roughed in some connections to the stock frame.