Freeman loader model?

[ACWD45]

I have an old freeman loader, and I have no Idea what model it is! I have never seen another loader like it, close but no. It will fit on both my Grandpa's D17, and my WD45. I have been told by bush hog that it might have been a prototype, or produced in very limmited numbers. If you could help me, it would be great!

Here it is off the tracter while the engine was being worked on.. Behind it, is my grandpa's freeman.