Use the(4 bolt)side cover from the original trans if the one on the OD is indexed differently. It's probably a good time to replace the clutch. Install the electrical components, kick down switch & bracket, pull cable & drive it. Best kept secret on how to make these old trucks more efficient.
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