It looks like the 55-2nd & 56 windshield washer units were foot-operated; and, the 57 unit was available push-button or foot-operated (USA trucks).
55-2nd/56 on left & 57 on right For those of you who are interested in reproduction Truck Data Books, a 1957 book is available, but the quality of the scanned pages are not as good as in the 49 and 54 reproduction TDBs.
