I'm not a locomotive expert by any means, and one of our colleagues from White River Productions, Dale Sanders, has posed a question I hope someone in the group can answer. Dale says:
I'm in the process of completing a two-volume pair of books covering Northern Pacific's diesel fleet. While gathering photographs for the project, I've come across a photo for which I have no explanation. The NP modified one of their freight service F7Bs with a unique roof hatch extension. See attached photo (the roof hatch extension in question is at the far right). None of my living NP experts have an explanation for this modification.
Then, I came across the attached page from the April/May 1970 issue of X2200 South.
There is the same [or similar] roof hatch extension on a Southern F-unit, again with no explanation. I'm hoping you may be able to answer the question that has been haunting me for some time now. Why did the Southern (and the NP) make this modification?
Any insights will be welcome - I'll pass them on to Dale.