I am pretty sure I have a book that will give me the accurate information, and will get back to you unless someone comes in earlier. Think the NW’s and the F7B were off the roster by early 1970’s. Much of the F’s went into remanufacturing at EMD into GP=18’s, if I remember correctly.
From EQUIPMENT OF THE BOSTON & MAINE, VOL I DIESEL SWITCHERS AND ROAD SWITCHERS, VOL II DIESEL CAB UNITS, Liljestrand and Sweetland, Bob’s Photo, 37 Spring St. Amherst CT 06401
The GP-9’s reused the parts from FT’s, the GP-18’s from the four BL-2’s, one F-2. and one F7A. F7B 4265B was operational in 1976.
Without explicitly stating, all NW’s were off the roster by the early 1970’s because later models had already been scrapped.
S-2’s went out about 1966, and I imagine S3’s didn’t last more than six or seven years more.
But the S-5m’s and S4’s were probably represented in 1976.
RS-3 1535 had a longer life than most and was scrapped in 1971. Pretty sure 1518 was gone by then.
Hope this helps. Books are great for dates built but sketchy as to retirements.
Again, there was a photo of this locomotive in the VOL 2 of the books I noted as operational in 1976. You could write Bob’s photo and they might tell you its dates for removal from service and scrapping. I would guess 1977 or 1978.