Mike,
You were very correct!
I got the skinny on the F7. It was never in service on the URR. It was somebody playing around. The URR herald was only on for the photo.
Dave
I was wondering about that one myself! With all the borrowed/secondhand power the URR has had over the years, like the Bessemer SD38's and the EJ&E SD9/18, an F unit creeping in wouldn't have surprised me. That pic had me curious, but I never had the time to do any research on it. Thanks for checking into it!