First off, this is a very interesting and seems to be a unique PHD. There is so much that we DO NOT know about some implements that were built for a Cub or modified for use on a Cub it would boggle the mind methinks. So anything we can learn about any implement is a good thing.
The more we learn about this particular unit, just may increase it's value which would be of benefit to your friend and his family in his time of need. Believe me, I know how expensive health costs can be, not just on the pocket book but on the family as well.
So .. here are some more pics
Suggest areas to look for identifying marks would be on the side of the gearbox. There may be "chop marks" on the frame parts as well. These can be anything from a series of dots/punch marks to chisel marks or even weld marks. Anything interesting that might pop up to possibly help identify would be useful. Same with the paint ... what appears original and what appears painted over if any.,
Unfortunately this appears to be a 3-point configuration and as was pointed out..... quite apparent actually as the mounting pins are obvious. I should have caught it right off, but missed it, apologize for that.
This doesn't mean this unit does not have value, it just does not have the value usually associated with Cub Post Hole Diggers. I would suggest that you do change your