All Chevrolet Powerglide transmissions had two gears.Of course the early Powerglide vehicles (1950 Chevrolet passenger cars) had different types of brakes than the disc brakes (with ABS) that are used today.
Truck Hydra-Matic transmissions (1953 in GMC and 1954 in Chevrolet trucks) were used with the same brakes as manual transmission trucks. The 4th gear is a 1:1 drive just as in the 3 and 4 speed transmissions. First gear in the Hydra-Matics is not as low as the first gear in a standard (SM420) 3-speed. The transmission shifts from 1st to second at around 5 mph (it can be adjusted but the adjustable difference is minimal for the first-to-second shift point).
Tim
