The Pennsylvania Railroad built 1,650 of these cars in 1930 and 1931. More than 35% of the series remained in service at the time of the Penn Central merger, and a number continued generating revenue in the Conrail era.

Lehigh Valley obtained fifty of the G26 class from the Pennsylvania in the early 1930s to augment its mill gondola fleet.

The body and detail parts are injection molded plastic, while the underframe is diecast. The drop ends can be positioned either up or down. Intricate and accurate detail is present inside as well as outside. The model rides at the prototypically-correct height above the rails, on Micro-Trains® truck frames fitted with low-profile wheelsets. The style of truck frame utilized is specified with each model. The model is equipped with body-mounted Micro-Trains® #1015 couplers.

Operation of this model over curved trackage of less than 12½-inch radius is not recommended.