Need help with another date - Alamosa 1969?

This first photo was among those taken by my dad. As so often happens with cardboard mounted slides, I'm assuming this one got bent so it has been re-mounted in a plastic mount. Therefore it has no date on it, and I assume it's an original and not a purchased photo. Our third trip to Colorado was 1969, so I'm guessing it was taken then, but you folks will surely know. The engines are 488, 493(or 495???), 487 and 491.

The other shots are card-mounted, and the first shot taken at Cumbres has a firm 1969 date stamp. The stamp is indistinct on the last shot, but given the Cumbres subject I'm assuming it was 1969 as well.

Thanks,
Ralph