A 55-1 series truck would have an open driveline. The original transmission would be an SM318 Muncie with the 4 bolt side cover. The floor shift conversion would be aftermarket. The stock rear end would likely be a 3:90 ratio. An overdrive transmission was available from 55-65 which is a direct bolt in and will give better highway speeds. There are numerous options available including changing the rear end gears.
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