I believe the prototype truck was called "Commonwealth". I modeled mine years ago in HO by cutting the outrigger springs off old AHM six-wheelers and filing the area flat. Much more recently, I acquired 3 pairs of Walthers #933-1307 "Commonwealth Str. EQ Friction Bearing w/inside Stabilizing Bearing Truck". I've pretty much retired from modeling now though, so if anyone wants them, let me know. They were $12.98/pr then.
Walthers current O/L catalog says the above has been replaced by #920-2205, which look pretty close (see attached). And they are in stock now, at $14.98/pr.