Among other applications, these heavy duty six-wheel trucks were used by the Santa Fe on their "big dome" and hi-level diner cars. Kato and Bachmann both make N scale versions of this design.
The Kato version was made for their UP City of Los Angeles storage-mail and Santa Fe El Capitan dining cars -
Kato catalog #800122G (6-Wheel Truck, Gray, w/ Gray coupler - Clip mount, 1 ea).
Kato catalog #800122 (El Capitan 6-Wheel Diner Truck, Silver, w/ Silver coupler - Clip mount, 2 ea)
The Bachmann version was made for their 85' Full Dome Coach -