www.flatout-engineering.comThey sell vette IFS and IRS for many old trucks, check them out.
I am also thinking that one day (time and money...), my 57 Suburban will get this. I am sure the ride would really improve a lot, maybe not down the Interstate or around the fairground, but pretty much anywhere else. I have several vehicles with a stiff rear axle and am certainly tired of the way they all ride (speed bumps, bad roads, sharp turns...), compared to all the vehicles with factory IRS I have driven, even old. An IRS can only improve things!