800 hitch part on ebay

Actually the two upper arms of the 800 series hitches can be used in a manner that closely emulates a single top link in a conventional 3 point hitch.

Just remove the evener bar and attach each upper arm on the oustside of the implement masthead and run a pin through all three pieces. Works quite well.

There are three different versions of the 800 hitch - 800, 800a and 801. 1953 to 1955 and then there was a 801 upgrade kit to upgrade the 800 and 800a to an 801 so you will see all kinds of configurations of these hitches. There are three different versions of the crank arms that attach to the rocker arms as well.

For pictures of all these hitches and associated implements see:
Link