1971 C10 Temperature and Oil Pressure Sensor

Trying to identify which sensor is which for sure.  This is a 250 I6 engine and I see two sensors on top of the engine.  One right at the thermostat housing which I believe is the water temp sensor, and another screwed into the head near the carb.  I'm guessing here, trying to be sure, any help is appreciated.  

I’m have not worked on one of these in a while but if the sensor is mounted as close to the thermostat housing as you say then it’s probably a temperature sensor. Oil pressure sending units usually have an oddball end on them and in some cases a normal socket does not work on them. Oil pressure sending units are screwed directly into an oil passage in the block. They sit on the same end of the engine as the oil pump and usually have some oil coming out somewhere! Near the intake manifold could also be a vacuum line, but probably not a sensor unless it’s for smog. If you can pull what you think is the oil sending unit out of the engine, you’ll know right away what you have, just don’t start the engine! What you have not mentioned is why you need to know which is which. Are you having a problem with a gauge or an engine problem? Gauges can have their share of problems electrically, in the wires leading to the gauge or right in the dash, so replacing the sending unit may not solve anything.
If you want to change to aftermarket gauges there are two routes to go and everyone has an opinion on which kind is best. Both Mechanical and Electrical have their advantages and disadvantages. I like mechanical gauges. I think they are the real deal for any kind of built car or truck and are definitely harder to install. Electrical gauges only need a wire to operate (much easier to install) and are definitely the O.E. standard. Electrical gauges are no doubt very accurate, but I like the challenge of installing the mechanical, making it look good in the process and the basic pure technology they offer. Mechanical gauges also work with the key off, the only wire they need is for a light.
Good Luck and let us know what happens. HB