For me, I have adjusted to my '38 as a town cruiser. An overdrive won't fit through the x-frame tunnel of a '38 or a '37 without cutting and modifying the frame. That may be the case to install a powerflight also...too big. The original three on the floor is a small tranny.
I really am satisfied driving around town and cruising the coutry roads around here. the other option is to have a T-5 or a higher rear end if it's important to do freeway driving.
Ray, you probably meant your message for carb37, but anyway...
Best, Jim