55-57 trucks used a different electric wiper motor than a 58/59. 55-57 also uses a cable operated switch vs an electric switch on the later trucks. I believe the mounting is different as well.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine