This was a rumor that got started in the Conway Scenic thread in the New England forum. So far, I've seen nothing concrete to back it up... but who the heck knows. Realistically speaking, one has to keep in mind that Pan Am has been selling off equipment that they don't use on a regular basis... and that includes passenger cars. Why would they sell passenger cars and then turn around and buy passenger locomotives? Makes no sense at all. But could they do something that shocks us and goes against everything they've done in the past? It's not entirely out of the realm of possibility.
The only marginally
plausible reason I can think of for Pan Am to buy F units would be to salvage the engines, generators, traction motors, trucks, etc., all of which could be used to rebuild some of the GP7s or GP9s. I just can't imagine them buying a pair of locomotives only to keep them in storage for 362 days a year. Maybe they're thinking of running a tourist train.
The passenger cars (the two that they still own) are stored at Waterville.
Please see the following thread for more info:
Business Train Sighting, and History of the Business Train