AC D19 Thermostat..........

[Goose]

Can anyone tell me where the thermostat is located on a D19 diesel? The temp isn't coming up on mine, and after I'd worked it awhile on a shredder a laser thermometer on the radiator hose only read 120 degrees, and on the engine block 150 degrees, so it's apparently the thermostat at fault rather than the gauge. The gauge always has read 180 when warmed all the way up.

I went through both my owner's manual and shop manual and the only mention of a thermostat was that the temperature is thermostatically controlled, not one word about where the heck the thermostat is located.

Thanks in advance.