I do not know the exact date of the last steam operation on the St. Lawrence Division, but the book "Hojack" documents the month as October 1948, which includes this date. That's when the Alco FA's began running on BP-1 and PB-2 (Benson Mines - Pittsburgh). One advantage of the diesels was that they could also be and were used on the daily turn of PB-2 BP-1 from Watertown (Massey Yard) to Benson Mines and Newton Falls (paper mill) and return, while L-2's were restricted from the Newton Falls Branch. I rode the engine on that BP-1 turn from Harrisville to Massey Yard one afternoon in 1965, with two FA's.