Does anyone make a kit to install a late model Challenger IRS suspension under a 67-69 A Body??? If I buy a car for the engine it's a shame not to use as much of it as I can to upgrade an older car!!
You will have to cut out the complete trunk area and rear floor area . Then, major modifications to the rear frame rails to build mounting structure for the rear IRS cradle. Then , as Yunick13 mentioned, the rear track width has to be taken into consideration. I'm pretty sure the rear cradle is a Mercedes Benz E-Class design left over from the merger so you would have your work cut out for you. I watch the Martin Bros. and Kindigit fabricate these all the time on their shows and it takes incredible skill and the proper facilities to pull it off.