Welcome!
As Greg noted, your 195D was originally sold by Yanmar-USA when they had dealers here. It is the same as YM1700D with some minor differences for the North American market, like the throttle lever is push rather than pull to accelerate, labels and manuals in English, and it probably came with adjustable width wheels and an overrun clutch in the PTO.
YM240 was similar to YM195 with slightly higher HP. That has larger-bore sleeves in the identical block and a water pump replacing thermosyphon. Both models share a single set of documentation - Operation Manual, Service Manual, etc. It looks to me that YM195 was introduced in North America simultaneous with the final version ('revision level 4') of YM240.
You can find a lot of relevant posts here in the Yanmar forum if you look under YM1700 and YM2000, which were the Japanese home-market versions of the YM195 and YM240.
Also, take a look at the original 1979 YM240 sales brochure in my sig photos. Is your YM195D green like that?