I thought all the truck speedometers in 1938 were round. Weren't they? If yours is round, you might be able to adapt a GPS unit to yours. I'm doing that with the AD right now. To avoid having to chop up an original AD speedometer case, I'm making a new one just for the GPS unit. I've already done this, but when I did it before I didn't use a GPS unit. It will work and it will fit in the AD and if you don't want turn signal indicators in it, there will only be a connection for + (to ignition switch), one to ground and one for the high beam indicator (which will now be a small red led bulb) plus the GPS signal sensor (which I think may be able to hide under the dash). The lights will use the exact same setup as before and will snap into the same type holes as before.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
