A San Francisco Marmon-Herrington in a picture from the firm that manufactured the card holder (Yarder Manufacturing) on the front of the bus taken in the trolley coach yard behind the old Geary carhouse, known as the Presidio yard.
Marmon-Herrington 847 is part of the 740-849 series trolley coaches that arrived in 1950-51 and were the final order of 1940s-1950s Muni trolley coaches. Judging by pictures in "Inside Muni", these coaches were delivered with two piece destination signs.
The Twin Coach (609) in the background eventually also had two piece signs, so this picture would probably be early in the 1950s. No scratches or dents yet!
Paul Ward collection