Looks like you have all the parts... Or all the most important ones anyway...
Here is a short youtube clip showing how they trip & change...
Dearborn 10 14 Two Way Land Plow-Direction Changing Automatically.AVI - YouTube
Fun small plow & Very practical ... KennyV
What do you plan on using this plow for? Do you have trenching to do?
Ok then I totally don't know what that plow will do because it looks like it throws the dirt two ways and leaves an empty spot it the center. :confused3: