Hopefully this will help someone. I had a water leak coming from the water neck and couldnt figure out why. I reinstalled the water neck twice and same thing. On the third time I looked closely at the gasket, it showed evidence that the thermostat was slipping when I was attaching the water neck and fell just below the circular ridge that you put the thermostat in. Then I noticed on the water neck (chrome one) that the circular ridge machined into the water neck was not very deep and the thermostat was protruding and not flush with the water neck. So I got an old fashion iron water neck. It was machined deep and the thermostat did not protrude from the water neck. Then I put 4 small dots of gasket sealer to hold the thermostat in place during assembly. Problem was resolved.
I have always used a rubber band and stick to hold it like shown on here. http://mmb.maverick.to/showthread.php?t=52814
