My slant 6 Demon (no A/C) has also heater core fittings of different diameters
I have had to install a smaller ring on the left hose to avoid a liquid leak. View attachment 1715934475
A smaller ring? What do you mean? I have this same bridge to cross too. My intake fitting is 1/2" but the heater box is 5/8" so I need to adapt something somehow or sttrreeeettcchh some 1/2" hose over it.