Crankshaft position sensor location needed

Car has been starting fine, but shuts off within a few minutes by the time it gets close to operating temperature. Symptoms sounded like ignition control mod or crankshaft position sensor. I changed out the ignition control mod and car started up and ran great for about 4 minutes, then shut off again. Now won't start, which is another symptom of crank position sensor. Can't find location of the crank position sensor. Some sites say between engine and transmission on back of engine, but I can't see it. Do you have to remove something else to see it and get to it? Thanks for any help on this one.