Googling photo's of CN GP9's, it appears they were set up for long hood forward operation. I couldn't find any "F" on the frames, but the bell was located on the end or the long hood. It looks like some may have been reconfigured for short hood forward when the "stripes" paint scheme came into being.
Or possibly they were equipped with dual controls. That's a question for a CN expert.
Definitely changed to short hood forward when the nose was chopped.
Rusty