This info from notes compiled mainly by Earl Knoob. Note that 492 ran through 1966, 497 ran through 1967, and the final two 493 and 498 ran in 1968, with 498 operating the most. My first trip to narrow gauge land was 1956, and we rode a RMRRC trip behind 490. It was kinda cool my dad had a film clip of me climbing into the cab while stopped in Antonito.
490 out of service pre-1961
491 4/19/63
492 11/--/66
493 7/24/68
494 5/14/62
I was informed that 494 was seen hot in Durango in June, 1962. She made her last trip east from Chama to Alamosa on 8/3/62.
495 1/28/61
496 1954
497 12/26/67
498 8/28/68
499 12/4/63