Small thermostat and water neck housing on my M1 Inlet

Thanks for reply Locomotion. I heard they changed them in 79. I think I found one on Rock Auto online catalog. It certainly looks different (and less substantial) than the ones I am used to using. Have a look here and expand the pictures, especially the one that also shows the gasket. Looks almost like pressed tin! But seems that is the one I will have to buy.

1984 DODGE DIPLOMAT 5.2L 318cid V8 Thermostat Housing / Water Outlet | RockAuto