[zzmac]

Mystery Solved!! I want to thank everyone for their input especially Peter Sellers aka Tom Wells for his "Shot in the Dark"!

The edge of the thermostat has (had) a tiny ridge around the perimeter that made it sit slightly above the thermostat housing. So I took a 5lb hammer and flattened it out. I put everything back together with two new FelPro gaskets and NO sealant of any kind and no leaks. I thought Tom might be on to something because the only other time it didn't leak during this ordeal was when I left the thermostat out.

The funny thing about this is that the thermostat fit better too once I flattened out the edges as it now almost fits snug. And what's puzzling is the thermostat I installed is the same size as the original one and my old Mr. Gasket housing has the same wider indentation as the new housing and the ridge of the thermostat sits slightly above on that one too. Maybe that's why I would get some small leaks on & off over the last few years.

I'm glad that's over with! lol Time for a big drink!