I just bought a 98 z24, it wasnt heating up so I pulled the thermostat housing to find that there wasnt a thermostat in it, so I bought one only to find that it is way smaller than the hole in the head, so thinking that they had given me the wrong part, I went back to the parts store and they searched every thermostat for a 2.4 and a 2.2 from 95 to 2000 and they were all the same. Is there a part missing in the head or any ideas?