Hi Dan,
   I don't know what the model of the cultivators on the 77 is. This is not the manual set... these were the successors to those as these are hydraulic.  I have another set still on a pallet that I got from a fella this summer that are for a Hart-Parr 70 and these are manual.... I am sure they would be the same as yours. In spite of the manual/hydraulic thing, they are virtually the same. I went to the Dover, Ohio Oliver show and saw some manual cultivators all mounted, so I took pictures of them. I can send you the pictures if you like. You would certainly be welcome to stop down and see the cultivators I have. Where in Mass. are you?
                             Cal