The 21-foot On30 McKeen. This is very, very loosely based on the first McKeen built, a 2-axle standard gauge railcar for the Union Pacific. There are 3 body choices, wood sided passenger or freight and steel sided passenger. There are two different chassis choices, one for the Lambert Locomotive Works Stalwart drive, the other for the Bachmann On30 trolley drive.
The proportions of the chassis for the Stalwart drive match the prototype proportion better, but it requires larger radius curves and a bit more work to build. The chassis for the Trolley is pretty much a drop in. You can also choose whether you want a standard or snowplow pilot. The Stalwart drive chassis also has and opening for a Tony's Train Exchange 15mmx11mm sugar cube speaker enclosure.