Considering the age of the tractor, I'd try to find a salvage set.
Here's one place I kept bookmarked - never used them, so buyer beware, etc: West Kentucky Tractor Parts
I'm gonna go out on a limb here and suggest that parts from another model may be identical, or close enough.
I just don't know enough to tell you what to look for - maybe someone else on here can ...
can anyone with a Kubota B2150,B8200,orB9200 HST measure the bottom lift arms Length, center to center hole, and hole sizes and let me know Hopefully then I can find a 3 point kit Thanks Ken