What you have is the basic standard 3 speed transmission. The official name /number is a Muncie SM 318. It has a non syncro
first gear and was used in both cars and trucks with some configuration changes from 55 through 67.
Fred

Note: That one appears to have a 64 case according to the date code.

Last edited by rfs56trk; 08/18/2023 9:12 PM.
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