Marlin's parts, which I have sitting on the desk in front of me, are absolutely perfect. Better than the factory parts. The orifice in the brass plate has a very rounded entrance, it is very highly polished. The rounded entrance serves to guide the flange on the bottom of the thermostat into the orifice as thermostat extends open. The clearance between the flange and the orifice opening is tighter for a better "shut-off" of recirculated coolant. This is only possible because the parts are manufactured and fitted to a higher standard than the factory parts were.
People are buying these parts as fast as he can make them. I've never seen a complaint.
So ... as Marlin wrote, press the orifice in place, set the thermostat on top, bolt it all together .... and
rock 'n' roll!
