The later model Beech Tow pin is PN: 60-820029-1. Spruce has the late model RAPCO PMA'd version for ~$25 each. I have not found one for less.

If you find a Beech PMA Tow Pin for less, please let me know.

The hinge pin design is pictured below and is PN: 35-825106, 

You do have a spare tow pin in your plane, right?

By the way, the things that goes through the hole in the center of them are:

MS20392-1C23 Clevis Pin and an MS24665-132 Cotter Pin