C.T.S. Coolant temp sensor

[gmbwrenchn]

6000 Le 135k miles. '90
Is the coolant temp sensor in the water neck? Reason I'm asking is I had a code come up and used a code reader that will flash the engine service light, then match up the flashes with the code in there book. The book states it's a bad C.T.S. but they say it's in the engine block. Just want to make sure. Thanks.

[dcjredline]

Upper front of engine kind of behind the thermostat housing. Drivers side next to the Throttle Body.