None of the units had an "F" on either end (Some wierd Canadian thing?) but his end has a pilot, marker lights and a bell. That says "front" to me. Very likely the only RS-10 I ever saw.
August of 1969, the F-unit era on the SP was drawing to a close as #6337 emerges from Niles Canyon, just West of Sunol. Today, this right of way is the home of the Niles Canyon Railway
The Lake Superior Railroad Museum's ex-Soo Line GP30 runs light engine up the north shore of Lake Superior clearing the line prior to an empty coal train arriving for winter storage.