I saw this PA-22, http://www.trade-a-plane.com/clsfdspecs/843638 on Trade A Plane and thought it was interesting that it has an autopilot in it. Says it's a Brittain Accu-Trac Autopilot. You can see it above the stack in this pic. Dang thing has a GNS430 in it too!
Is this an STC for an autopilot or a 337 you think? I bet getting an AP approved is a pain in the butt, let alone getting it to work right.