The transmission section of the 59 (Muncie/4 bolt side cover) and your transmission would be the same. The internal parts are the same. The BW OD section replaces the tail shaft on the stock transmission. With the exception of Corvette's and a couple years of Pontiac's these early transmissions were identical. You can even use parts from the 58 through 67 transmissions with the short tail shaft. Lots of these units out there, I find them all the time.
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