Another thought would be a Clark overdrive transmission. I don’t know all of the ins and outs but I recall there being a few different options that would be a direct replacement mostly while keeping a stock appearance. Clark 207 VO?

Steve, is this for pleasure driving? I would wager if your just pleasure driving ect unloaded the truck with a 216 that’s properly tuned can handle the overdrive.

I have a 46 Chevy COE that I’ve dreamed about putting a overdrive in. Keep us posted.

~ Phillip
1949 GMC Suburban - 10 year project
1952 Pontiac Chieftain Convertible straight 8 hydramatic
1945 GMC half ton truck - Driver- Sold 9-15-25
1946 Chevy COE - SOLD 1-5-26 BUH BYE CHEVY!
1959 GMC Half ton long bed NAPCO