I love that old 350 and especially the fast hitch. I sow wheat on my garden and turn it under to rot out and it works great. RED POWER THEN...RED POWER NOW!
That hitch is called a Fast Hitch, and it's an IH design and only IH implements and attachments will work with it. BTW, I ran across a International 300 Utility a couple of weeks back. I don't know if it was for sale, but seem to be in decent shape. The 300 was a predecessor to the 350. Good tractors. They derived from the Farmall H and a McCormick Deering (I can't remember the model number). The International and the earlier McCormick tractors were the utility tractors while Farmall were the row crop tractors. A Farmall 350 would be the row crop version of your IH 350 Utility.
I work a 300 u for 20 seasons ,no better hitching than 2 point I h ,never left the seat , Here in north Florida Dixie 18 developed in Jefferson County,