I believe the 463 last ran in 54 or 55(We have the info in our 463 video, but I did not remember without looking).
The Silverton mixed looks to be fading here into more of a passenger train. The freight is either cinders for dumping at a bad spot en route to Silverton, or its company coal for Silverton. Can't really tell.
This could be a special train to Silverton, since there is a caboose right behind the freight car. Lots of times the caboose was up front for specials like the RMRRC trips.
We have some older footage in the 40's where there was only one combine and caboose, and the rest is all freight. Thus I suspect this is late in the game for 463!
Greg