The 50 foot refrigerator car is in company ice service.  Typically when a car is reclassified from revenue service into company service the reporting marks are changed from SFRD to ATSF.  Interesting that this car did not have the reporting marks changed from SFRD to  ATSF. 

 The car classification was probably Rr-37  and was a super insulated car rebuilt from Rr-10.  The super insulated cars were in frozen food service until displaced by the MTC cars.  In company ice service the car was reclassified Ie-R.  There were several shots of this car which have appeared on ebay.  The car classification shows up clearly in other shots. 

My guess is that the photo is probably from the late1960s.

John B. Moore, Jr.
Albuquerque