I substituted brass rod for the original axles, regauged to 0 Gauge, with new 33" wheels (2-rail) added. The old drive gears fit the new axles.
The old sideframes were modified by cutting away the suspension spring and brake detail. New coil springs were made by making a mold with silicon putty over part of an old freight car truck. Castings were made with metal filled epoxy. Apparently the epoxy and moldmaking putty date to the late '80s or early '90s! Still works. New sideframe detail was added with strip styrene.