Bill.
If you like the car body, Atlas O sells three-rail trucks that screw to the chassis like the two-rail on most cars. Removal of the coupler box is necessary. Watch for the spring for the coupler as you open the box. I use two small screw drivers to pop the coupler box tab. The only cars that do not convert are Steam Era box cars that have a different floor truss height that creates a different clearance. All modern era cars are able to have trucks switched. I have probably done 75 cars in my collection in order to get the car bodies I wanted.
Sincerely, John Rowlen
