In 1970, CP embarked on a progam to rebuild its aging fleet of GP9 road switchers. The locomotives had their front noses chopped along with many other appearance details change. The later rebuilds would receive upgraded 645 power assemblies. The rebuild program lasted until 1988 and ushered in the plain CP Rail red scheme.

Starting in 1993, CP converted various end-cab switchers to "daughter" units, or slugs, by decommissioning or removing the prime mover (replacing it with ballast to return the unit to its operating weight) and drawing power for the traction motors from GP9u "mother" units using cables that were semi-permanently connected between the units. All of the mother units were drawn from the 1500/1600 series of GP9u units.

The Rapido Trains HO Scale CP Chop Nose GP9u locomotive features:
Heavy diecast frame with super detailed piping and traction cables
Detailed Blomberg trucks (Later series have rotating bearing