So this is pretty cool: https://www.google.com/amp/www.hotrod.com/articles/bolt-corvette-irs-suspension-project/amp/

Looks like a much more cost effective solution for those who would love an IRS in the back of their car but can't afford Heidt's or Art Morrison's prices. I priced it out, and the IRS, Dobbertin's adapter kit, a used Camaro rear diff and Dobbertin mounting kit, upgraded C6 axles, and a custom one-piece driveshaft will cost around 5.5-6.5 grand altogether. Seems like a fairly good and effective deal to me, if you don't mind using GM parts in your old Mopar.