Install bus style cabin heater with 2.3 Ford omc

[Touchinbottom]

hey there, I have a 1989 spectrum I/o and am looking to install a simple bus heater off the return water from the engine cirdlculation. Any suggestions which hoses I tee off ?

 

[Scott Danforth]

Lower radiator hose and thermostat housing before the thermostat.

Make sure its a marine rated core, or it will corrode