Where is the temp sending unit?

[Agent_4573]

Ok, so i went to put in the new sending unit and it wouldn't fit all the way in. I compared it to the stock one and it was bigger so I was gonna put taht one back in. Then i realized that it didn't screw all the way in either. I put the new one back in and tightened it up. Now I was going to take a temp reading to see if the gauge was off or not. I was told to take off the radiator cap, start the car and let it warm up and then put a thermometer in the radiator. Only problem is when i tried this, i started the car and came inside for 5 minutes, when i went back over a gallon of coolant was on the ground and it was still coming out. So i thought hey, left put the cap on half way so it doesn't pressurize, but doesn't spill either. I did that, then it started pouring out the overflow. So to make a long question longer, how do you get a temperture reading of the engine/coolant?