4 engines in July, 1967 in Chama

I tried to do a search and had no luck. I am pretty certain Jimmy Blouch sent me the info on these two days of operation, but I cannot find it.

July 10, 1967
497 and 498 Alamosa to Chama

July 11, 1967
493(From Durango) and 497 go back east to Alamosa
498 goes to Durango

While looking at the Chama morning footage I just noted a 4th engine that was behind 498 at the coaling tower. Looking at the tender it appears to be a K-36.
So my questions are:

Did this 4th engine actually go out with 498 as a helper to Durango on July 11th?

Or did the engine stay in Chama for some unknown reason?

What engine was it, if it is listed somewhere in the archives for that day?

Thanks in Advance
Greg Scholl