They both appear to be between Hesperia and Lugo, heading railroad westbound. The first pic looks closer to Hysteria proper as the running track was (is?) closer to the Natural Crossover than it is to Lugo. The second pic looks closer to Lugo, and well into the grade. If I'm not mistaken, radio controlled help was experimental. I don't know how often or when it exactly occurred; all the pix my dad took around that time between Cajon/San Berdoo and Kaiser didn't have any RC units, except for the SP, which was a borrowed BN set-up.

What few AT old heads I've spoken to in the past indicated it was prone to screwing up and was occasionally known for not coming out of power when the head end notched-off.

I would also agree this is coal bound for the now-since-removed coal fired smelter at Kaiser Steel- a combined effort with SP bringing ore from the Eagle Mountain mine.

As an aside, Kaiser Steel, although long gone in name is still producing steel products under the name California Steel Industries from ingots brought in from overseas and is still BNSF (and I think UP, too) served.