I ordered a new thermostat for my hemi project. The ousing has casting number 2780987. I ordered a thermostat for 69 440/383 which should have worked for that housing. IIRC, the housing was used from 67 to 70. When I place the thermostat on th ehousing it partially falls in. The thermostat is about 2" in diameter. I recall wider thermostats in last project. A wider one would sit in the recess on the water neck nicely and sit on the housing without falling in. Is this a common issue? I am guessing the thermostat is a generic listed part at NAPA. I wont be able to get there until Tuesday. Is there another part to use? Thanks.