Old Style and New Style Thermostats

[WGuaire]

Yesterday I replaced the cross over automotive thermostat with the current OEM Yamaha part. It was a DUH moment.
The middle photo shows the old Yamaha 'stat and the crossover automotive thermostat.
 
  The old stats have a hole in the face. The seal that seats on the face has a square opening to allow for the coolant flow through the hole.
  The new thermostat has no hole on the face. The new gasket has no square opening. It completely covers the round face of the thermostat.

Be advised not to mix the old and new ones!
I put a pink dot on the old style one to show the new thermostat's hole.