Two-piece fully equalized trucks mount with a #2 or 2-56 screw, sold separately. The self-centering action trucks self align themselves parallel with the car for easier placement on track. The Bettendorf double truss truck was introduced in the 1930s by U.S. railroads and was allowed to be used in interchange service through 1993. The Kadee #500, #502 & #550 represent 50-ton trucks for 100,000 pound cars. Truck Features: * Self Centering Action - Trucks self align themselves parallel with the car for easier placement on track * Code 110 (.110) 33′ ribbed back wheels * HGC weighs nearly the same as metal trucks * Superior rolling ability * Brake pads * Accurate markings * Incredible detail true to prototype * Non-magnetic metal wheels * Highly flexible fully equalized trucks * Smooth tracking free rolling contoured insulated axles * RP-25 free rolling wheels