In the fall of 1943, the 941st Field Artillery deployed from Camp Polk LA to the Desert Training Center at Freda CA on Santa Fe's Parker Branch.  I found a memorandum copy of the Government Bill of Lading in the National Archives and have written a short blog post that includes images of the seven page GBL and a link to a spread sheet with the car numbers and loads.

Not quite over Cajon, but a typical artillery unit move for 1943.  The personnel would have gone in a separate Passenger MAIN train.