I believe the steel beam plow was a Salida invention. There were several of them. Because they used the standard pilot beam, they could be removed more easily and came on and off more regularly.
My take on 489 with her nose in the dirt in Antonito is the track in front of the engine house, which has had engines parked on it for years, has sunk and needs a bit of a lift. The pic of 489 in Chama shows plenty of clearance for the plow. If indeed the plow is riding low, tightening up the braces will raise the nose of the plow.
Off the end of Lobato Trestle, the grade picks right up - right off the end of the bridge. I remember standing there waiting for 487 to come across so I could send the helper back to the joint. 487 would hit the end of the bridge and the point of the plow would literally drag on the rails for a few feet until the rest of the engine was into the increasing grade.
That's what you call a "vertical curve".
....still don't understand why 487 didn't short out the whole railroad when it did that. My HOn3 version sure as hell did...