In 1872, the Denver & Rio Grande ordered its first conventional 8-wheel freight cars. These are the 3'2" wheelbase trucks used under those cars. They were equipped with 20" diameter wheels and had truck mounted brakes at only one end of the car. Essentially, this item includes the ironwork for the trucks...less wheels and timbers. To complete, scale lumber is needed to create the truck bolster, spring plank, and brake beams...plus styrene strip for the transoms on which the brake beams are mounted and wheelsets (such as Bachmann's 24.5mm diameter wheels)...Designed for White Strong & Plastic for maximum strength...detail materials will produce a smoother finish but at a higher price and reduced strength (Should still be plenty strong).