"The gentleman standing to the left I don't remember but the two men on the right are Roger Sunbath (next to the engine) and standing next to him with his hands on his knees is my father, Vince Hotchkiss.  I think this is at the shop in Los Angeles, CA."

(9-11-11)   From Davey Jordan:

"Vince Hotchkiss' son is correct for the mystery mechanics, but Roger's last name is Subith."