Been thinking about putting an I.R.S. under the '39 and researching what is out there. Because the '39 has a back seat I want to use air bags to adjust the ride in case of passengers, this rules out 'Vette rears. Lake model Jags look good and would lend themselves to bags in place of the coil springs. Late Model Mustangs (2015 up) also look good and not to wide. Ford Navigator and Expedition look good but would require narrowing. That's where I'm stuck, nobody seems to know anything about narrowing an I.R.S. Anyone have thoughts and inputs?