Troy Bilt/ MTD still makes the PTO model horse, which I think is actually a Horse III, and an upgraded version, but they basically start at $2,500. and they did shrink some parts in the gear case/ axles
I recently repowered my grandfathers old 2spd that the old Techumseh 6hp was dead which I inherited. Carb missing parts, no spark, has an SSI module and they are NLA. I bolted on a Briggs XR 9.50 commercial and actually bought the bumper guard for the newer Horse that Troy Bilt sells now as they clear the OHV engines.. After sitting 10 years and changing the gear oil after sourcing the correct GL4 140W it's ready for service in the spring. I may put a new set of tines on it but I think they are ok