You can use the side cover from an earlier truck on your trans since they both have the up/down configuration.
However, you will need to use the L/R shift fork from the TF side cover as the shift fork on the AD trans is narrower to accommodate the narrower slider gear.
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