Actually the 51-54 pass car will work on the 1/2 ton pickup. The hub and spindle are longer than the 55-57 car. It still would be better to convert to disc's if you are going to have some serious HP.
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