Many of the Japan made tillers and tractors have them. You would need to find the length and the number of spline teeth your tractor and tiller uses.
Mitsubishi, Satoh, Yanmar, Kubota, Iseki, Shibarua, Hinomoto, etc would be good candidates to seek out for possible short shafts.
Some of the Yanmar message threads here on TBN have had people make a few universal versions out of automotive 4wd parts in case you need to fabricate something easy. So go here and do a sub-forum search on tiller PTO dive shafts.
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