FAA STC
FAA STC was issued to Casey Copter Acessories, Montreal oct. 16., 1975 under number SH1018EA Later amended several times. Try Google.
Installation instructions from Casey already contained instructions for removal of Janitrol heater, if previously installed.
Instructions contains list of parts - from Casey and also list of Bell parts required for heater installation.
Also additional requirements for maintenance included. (every 100, 300 and 600FH plus CO indicator replacement.)
Have no idea who owns STC for B206 now, but it seems that some parts of original STC were taken by other vendors, as original STC was for different versions of Jet Ranger and Long Ranger.
Hope this helps a bit.
hoistop