Read this thread for a method to tap into the tractor hydraulics. Just the first few posts should be enough.
Back in stock. CDN$40 plus actual shipping These are obsolete and no longer available. I have recently been contacted by a member asking if I will make him one of these after reading how I made mine. I know this comes up from time to time and would like to gauge the interest others might have...
www.orangetractortalks.com
Most of the backhoes that are 3 point mounted probably had a rear mounted PTO pump and a hydraulic tank on the hoe somewhere. Then that would power the valves on the backhoe. Do you have that or are you trying to use the tractor hydraulics?
There is also supposed to be some enforcement bracket for the top link bracket so that you don’t tear the tractor case apart.
I could not find information about a 505 backhoe so you might need to post pictures of what you have to get better help. And possibly post in the service section instead of the for sale section.