This would also apply for my topic on six axle power along with the Pennsy ALCO PA demonstrator.
As for the FM demos, there were originally four of them built in 1953: FM-1 to FM-4. The first two (FM-1 and FM-2) were dedicated for testing on the East Coast on railroads,
mainly in New Jersey, and likely for the Reading and
Jersey Central Railroads in addition to the LIRR. TM-1 and TM-2 were sold to the Wabash Railroad as 550 and 551, renumbered to Norfolk and Western 3598 and 3599, and were later scrapped likely around the mid-1970s. Out of 127 of these locomotives built,
only CP 8905 survives at the Canadian Railway Museum in Saint-Constant, Quebec. Although I couldn't find further info for the demo's service on Long Island in particular, I was able to find this info on
this helpful Southern Pacific site.
"Look down, step over, and watch the gap!" - Dr. John Clarke, The Gap Rap (2010)