Designed in the 1980s, these high speed trucks were used on Amtrak's new fleet of MHC-2 (material handling) cars. Unlike the recycled BX Express trucks used on Amtrak's earlier MHC-1 cars, these trucks had a longer wheelbase and were specifically designed for passenger service. These trucks were also used on Amtrak's Horizon, Viewliner and Superliner II cars.
The design for these trucks was derived from the truck design used under the Metroliners back in the sixties. It was the Pennsylvania Railroad that insisted on a double-drop-equalizer design, and the result was... possibly the worst riding train ever! Still, as adapted to the Horizon, Viewliner and Superliner II cars, the results have been much better.
These GSI (nee GSC) passenger car trucks are not in any way derivative of the earlier BX express car truck. While they both do have clusters of coil springs between the drop equalizers and the frame, there is additional isolation between the frame and the bolster. That's what the central spring clusters are for. It is also interesting to note that double-drop-equalizer trucks were very popular during the thirties, but fell out of favor after the war. Then along came the BX express, the Metroliners, and then Amtrak. And now they are something of a de-facto standard.
Kato makes two versions of this same basic truck. Catalog #800081 (High-Speed Truck, Black w/ Coupler, 2 ea) was specifically designed for their Amtrak MHC-2 cars -
Kato catalog #800085 (High Speed Truck, Black w/ Coupler, 2 ea) was designed for Kato's Amtrak Viewliner sleeper -