You might give Agri Supply (1-800-345-0169) a call. PTO shafts can be made up of components. Probably if you give them a call and tell them what you need that could make it up and send it to you.
Agri Supply has 6 spline and 21 spline yokes. Japanese tillers have 19 or 6 spline yokes. If you have the 19 spline, you'll have to use the Japanese shaft.