I've tried to use a "search" and there a lot to read but I want something more specific. I may need a new thermostat for my '71 Mach 1 with 429CJ engine since it's been overheating when I'm on traffic/cruising on street. On freeway it seems fine. I live in "mojave desert" in Southern California which usally goes into 90's to 100's in spring to early fall. What would you suggest, 180 or 192 for thermostat? I will test my old thermostat to see if it is working or not but I just need a new one anyway. Thanks.