There were only 2 styles used on the Hs. The very early style with the smaller diameter shaft, and then the later style such as you have. The later style continued right up through the Super Hs. The Farmall 300 also used that later style, but the 300 also offered the optional, independent PTO.
I may be off a little. The independent PTO may not have been available until the introduction of the Farmall 350.