I found this information. Wow I learned something today.
(The rear suspension was also new and improved, with two primary trailing arms, carrying the coil springs. One additional upper control arm was used on the six cylinder and 283 V8 versions, and a second upper control arm with the 327 and larger V8 engines (and all wagons), to better control the motion forces under acceleration. The rear axle was a stronger Salisbury-type, and the driveshaft was now a one-piece unit. )
I'm sure there are many aftermarket companies or it would be a trip to an older salvage yard that hasn't crushed every old car.