Jim,
According to your pictures the rear housing is from a 58 up OD as it has the rear mount pad. It uses the short spedo gear. The earlier BW housings used a longer gear and adapter. Also the upper case normally uses a 1 1/2" flat expansion plug. Good job on the pictures and the write up.
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