Barry,
I found this site:
http://www.ntractorclub.com/cgi/view...anuals&th=5985
It includes the attached description of the hitch.
It seems Holland is still producing similar hitches, but there are some visual differences.
See this link for the modern production:
http://products.safholland.us/sites/.../cp-400-h.aspx
Best of luck in your search,
Colin