Yanmar made a YFL580 loader for the YM169(D) tractor. But the YM169D is quite a bit smaller than the YM180D.
It would require too much modification, in my opinion.
I have seen a picture of small Yanmar loader posted on here that was in Yanmar green,could have been model 80.It was actually a Johnson model 10 or 14 loader that must have been sold in the 70's by Yanmar dealer as Yanmar loader.