Matt,
The photo I believe you were referring to in your original post appears on page 36 of Twilight on the Narrow Gauge, by Frederick A. Kramer, photography by John Krause. The truck, parked at the Dulce station, appears to be a '52 or so Ford 3/4 ton utility truck. The lettering on the side says "D.&.R.G.W.R.R.", "Truck No. XX", and "Communications Dept." Not sure of the "Communications". I tried to attach a scan of the photo, but the file was too big and it's late at night so I didn't have time to fiddle with the resolution on the scan to get it below 200KB. Maybe someone else will post it, or I'll try again tomorrow, or, better yet, maybe you have access to the book mentioned above.