Operating Era: 1906-1953. Now includes our new one-piece roof frame. New and improved Decal artwork. Operating Era: 1906-1953. THIS SERIES NOW COMES WITH OUR NEW ONE-PIECE ROOF FRAME. Pacific Fruit Express. Built on the same underframe as the B-50-1/2/4 box car, these reefers were the first 6,600 installed on the newly formed PFE. The classes were distinguished only by externally invisible differences in ice bunkers. Delivered before the Safety Appliances act, the cars were upgraded in the early 'teens with ladder grabs on the ends and sheathing bolts on the sides.