NYS&W (former FJ&G) No. 100 was switching at Sangerfield, NY on Sept. 30, 1983. I'll let the diesel purists figure this one out. The tall cab window on the front of the cab and the fuel fill on the side of the cab would indicate it is a RS-2. The batteries being located on the walkway would indicate it is a RS-3. As best I can guess, it was once a boiler equipped RS-2 and the batteries were located on the walkway for added water capacity under the unit. I'll be the first to admit, I don't know which.