[ffindling]

An IRS assembly can probably be installed under most Cobra frames that
were originally designed for solid axle
installations. There are a number of
companies that offer package IRS assemblies in custom widths. RCC Specialty of Ft. Worth, TX has a package
IRS using a 9" center with Toronado spindles and half shafts in a double wishbone configuration available in custom
widths with a choice of inboard or outboard brakes. I think the price of their
IRS complete with pumpkin is around $4500. No doubt some fab work has to
be done to install one of these, but it
doesn't appear to be too difficult.

.....Fred