That makes sense then - I forgot about the 535. Is there a list that has the model number for the post '75 tractors? I have my what must be a '79 book then as it has the 545, but nothing else.
I would agree that it is a 753 hoe. On the 755, the pins that hold the end of the boom and stick cylinders to the top of the boom are further apart. I think on the 751 hoe, they actually share the same pin. I have a 4500 with the 755 hoe, and it is very light on the front. The 753 should be better.
By the looks of the valve bank under the seat, it has a Gannon setup to give you full control of the 3 pt hitch top link and side link. Probably had a box scraper on it at one time.
Ford didn't change much from 1965 up through the mid 90's, so a lot of the parts will interchange.