"If I had a 3 Point hitch, Couldn't I find a used backhoe that attaches to a 3 point hitch"
No. IMO Any 3 pt backhoe would look like a toy compared to the frame mounted 'hoe that is on it now. It would also be lighter, providing less ballast.
Topbuilder - Absolutely agree with you there! It would dig like a toy too - but they're not intended to be an alternative to a real 'hoe.
Additionally, the forces a 3PT-mounted 'hoe puts through the links and onto the tractor are horrendous - they can also be multiplied several times by the time they reach the mounting points on the tractor. I hate to think what these forces do to the links and castings of the tractor. They were never intended to cope with this type of use.
Jdeilus - Arc Weld is probably correct - The mounts for the 3PT may be there (and hydraulics it appears are), and it just needs the arms and links fitted to them. But you will need to remove the BH and mounting frame first - how much work is involved there?
I was really lucky - my loader has 3PT and PTO, although I suspect the wrong set were fitted - they don't lower at all close enough to the ground. I reckon you need the same 3PT link set as a MF65 or 165, (as I do too) not a 35 or 135 - they are too short. Let me know if you need further info.:thumbsup:
Important Note (and this IS important): - 
The 3PT hitch top link mount on any MF machine - can be used
only with agriculture-oriented implements.
It also can never be used as a towing hitch eg to attach a chain to pull a log or another vehicle or machine. This is really important to understand. They are designed to be very strong for push/pull loads eg ploughing, discing, slashing etc, but they are hollow in order to allow a linkage to connect to the draft control valve. Therefore they don't have much strength for side-forces or vertical forces. When using a lifting crane attachment etc, use the triple-mounts below it, on the rear casing, with the long flex-pin - but don't tow from there either. Use an under-slung towing hitch, or put a drawbar in the lower links, let them down low for some safety, and be careful.
These machines were built tough and durable enough to last for decades, but remember, they're now decades old too! They're still very capable, but be aware everything is well-worn nowadays. Ours are still capable enough to easily earn their keep. :laughing: :drink: