Good news,
My local avionics techs are on very good terms with STEC/Genesys and provided the STC paperwork - for free!
Also sourced a later model Midco turn coordinator which is brushless. All set and ready to install! - I am just going to hold off for 6-12 months on the install to see if Garmin will make the GFC500 available to the C150/C152 community.
I have seen the trio avionics autopilot setup - but it looks overly complicated for a rental aircraft (I plan on hiring this out). - I would not want someone to be flying in IMC without good mode awareness on the trio - it is not as user friendly as say the GFC500 coupled to a G3X Touch or the STEC units - which are fairly simple and straight forward.
