I doubt very much this is an "overdrive transmission"...
Most US pre-1950's truck four-speeds had this "reverse lock-out latch" lever...
I don't know about Ford and Dodge, but Chevy / GMC had the reverse latch through 1947; when the Advance Design trucks came out in mid-'47, they offerd the new SM-425 four-speed, which eliminated the reverse-latch, and put reverse "all the way towards the driver, overcoming a strong spring, and back towards the seat" (parallel to 2nd gear.)