I can't see why a 3-pt implement would/could be for a particular tractor, unless it's because of the paint color used.
The whole point of the sleeve hitch and 3-pt hitch is avoid proprietary hitches.
Gannon did make the Earthcavator with proprietary hitches, in fact the one I have is an example of that, but a 3-pt should be universal.
I did some searching, and Gannon is now a subsidiary of WOOD Manufacturing, but it appears that they only make box scrapers now.
A bit more searching, and I found some information on the Earthcavator trademark.
It was filed for on 5/31/1966, registered on 2/12/1968, and expired on 11/3/1992
Edited by OldBuzzard, November 26, 2013 - 10:25 PM.