According to the photo you posted, it has a 5 lug bolt pattern which was not available in a truck. 57 through mid 60's cars used a 3.36 rear axle ratio with an automatic transmission. That's likely what you have. 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
