Ya, There's a guy at the Wichita swap meet every year, that converts the model A torque tubes, with them.
I thought about trying to put a governor back on, and rewire, for semi automatic use, but I figured 1 or 2 good "under load" downshifts would be the end of it. Besides, the gear ratio seems to be fairly close the The TH400, so it isn't really like a splitter, more like an additional gear. 1st-over, is slightly lower than 2nd, and 2nd-over is slightly lower than 3rd, but you lose most of the difference, when shifting.
I think a 20% unit would be great for a splitter and overdrive.