The open Amtrak RFP is for bilevel. Nothing single level at present. Alstom built the Surfliners I think, and Bombardier some Superliners.
For single level LD CAF built the Viewliner 2s, Budd the Amfleets, Morrison-Knudsen the Viewliner 1s. Bombardier built Comets and Horizons (and LRC and...