Yes, 284 was in the consist. I've done some more research, and think I've discovered most of the consist; Departing Salida the cars were;
baggage car 164, coaches 284, 306 or 320, 280, 310 and "Silver Vista". Close examination of negatives and that color shot above at Mears Jct shows all three open platform cars had electric train lines on the roofs; 284 was in the consist next to the baggage car and definitely shows up in the photos, as does 310. The next coach has a roof similar to 284's, and has the conductor's window. Since it's not 284, it has to be 306 or 320. The third car was 280; there's a roster shot of it at Villa Grove on page 159 of Herb Danneman's "Rio Grande Narrow Gauge Varnish"; while the photo caption doesn't say it's 1950, I can't think of another fan trip that went down there, and the roof configuration is the same as in the photo at Mears Jct. Also of interest is that these cars must have been shopped shortly after this fan trip, getting repainted Grande Gold along with combine 212. Now if I could just find a photo showing that middle open platform coach number!
Best regards,
Wayne Hills