The "C.S." stands for cast steel, which describes most trucks.

  I've felt these are late versions of Bettendorf T Section trucks, where instead of the upper chords terminating at the upper inboard corners of the journal boxes, the top profile extends over the boxes and curves down into the upper outer corners.  The whole side frame profile is similar to early U section one piece side frames.

Brian Leppert
Tahoe Model Works
Carson City, NV