In 1974, ACF(R) built the first box car for Railbox, a subsidiary of the Trailer Train Company. They went on to produce 5,400 50' cars over the next six years, receiving large orders from Class I railroads, shortlines and box car leasing companies. These box cars have a 50' 6" interior length designed to fit slightly larger Plate C dimensions. This yielded a capacity of nearly 5,300 cubic feet. Most of the cars were built with non-cushioned underframes.

Features include:

* Prototypical non-terminating corrugated ends
* Diagonal paneled roof
* Single 10-foot YSD design sliding door (non-operating)
* Detailed cross-member attachment rivets on the side sills
* Weighted, detailed underframes
* True scale dimensions with accurate details
* Equipped with AccuMate(R) knuckle couplers
AccuMate(R) couplers are made under license from AccuRail Inc.