I am sure the only reason 499 was sent is that it was the least attractive for restoration. Otherwise why would D&S get rid of it. 493 and 498 have history too, since they were the last 490's to operate in regular service. I saw them both and chased them in 1968. They were together in Chama with 483 in fact overnight.
I recall hearing the rumors about the 486 going to Durango, and at the time some thought the C&TS might somehow be involved in that deal, but nothing ever materialized. I suspect D&S had to kick in some funds to get 486, otherwise why would the Royal Gorge folks fool around with it at all!!
Just my opinion.
Greg