"Torpedo Tube" GP-9s assigned to freight or passenger?

When ordered and delivered, where the Central's TT GP-9s (drsp-9a, -c, and -g) designated as "dual purpose" units or where they dedicated to the passenger/M&E power pool? I recently read a caption in a NYC picture book that described them as dual purpose. I thought they (especially subclass "c", the big 1956 order) were bought to kill-off whatever passenger steam was left on Lines West and were mainly assigned to passenger runs until they were re-geared for freight operations.

thanks,

Bill