This thread really helped me with replacing the crankshaft sensor on my car.
First, from what one auto parts store told me, the government made all car manufactureres conform to one set of codes in order to make devices like the OBD work for all vehicles. Shops and manufacturers probably hate this because it helps people find problems with their car instead of having to go to a shop and pay 100s of dollars for simple replacement part fixes. The OBD II for my Saturn said I needed a camshaft sensor and also listed a number of other error codes. I bought a crankshaft sensor and the camshaft sensor error code and all the other error codes no longer show up on the OBD II. If the sensor is at the bottom of the engine, it's a crankshaft sensor. If it's near the top of the engine, it's a camshaft sensor.
The crankshaft sensor on a Saturn SL2 1996 is a black plastic covered cylinder shaped device, 3 1/2 inches long by 3/4 " diameter.
It's located above the starter but foward so you can't see it unless you use a mirror, which is what I did. Obviously you'll have to look at your new sensor in order to know what you're looking for when trying to find the old sensor on your car. You'll probably need a flash light to do the job. Don't take the wire connection off the sensor until you have it pulled out of the engine block; it can be difficult to pull the sensor out and the connector helps get a grip on it.
More propaganda. Forget you ever heard "the crankshaft sensor rarely goes bad". That statement is designed to get you to take your car to the shop. The crankshaft sensor is only $15, less than new plug wires. The guy on this page
http://www.aa1car.com/library/saturn04.htm spent a bunch of money on an ignition module and plug wires and wasted time doing all sorts of electrical testing only to find he only needed a $15 crankshaft sensor. If your car has a lot of miles on it (75,000) and you're getting the P0341 code, the crankshaft sensor should be the first part you change - not the last part you change.
No matter what a mechanic or a car manufacturer tells you, always consider the opposite. The crankshaft sensor doesn't last any longer than any other sensor.