Very excited to see these released!
The Prairie Shadows/Rapido gondola represents the drop end cars built for CN and CP by National Steel Car during the 1950s - 52'-6" with Z channel stiffeners. Unfortunately they did not offer the fixed end version operated by PGE/BCR, so Jeff's ends solves that omission.
The chip car extension kit represents the sixty cars converted by PGE in 1961-19621. CP undertook similar conversions.
Tim