Where is the crankshaft position sensor located?

Why was the crankshaft position sensor replaced? The engine won't start or run if it is defective.

" I was told that because it had been replaced it would probably only last a week but could last longer"

This doesn't make sense. Who would perform a repair that will only last a week? What logic leads to expecting a part to fail because it was replaced? We replace sensors and other parts all day long on dozens of cars. How many of them do you see sitting on the side of the road because their week is up?

Unless you can add something that suggests something is going to fail, a car you're afraid to drive is hardly a car worth owning. My SUSPICION is you're worried about something that doesn't warrant being worried.

Dandy. That makes sense for replacing the sensor, but I haven't heard of repeat failures, especially not caused by the clutch. Often aftermarket replacement parts are improved to prevent whatever caused the original part to fail, but sometimes those parts have a design flaw that causes early failure. Your mechanic may be jittery or nervous because he ran into one failure of a new part, but in reality, that happens to us all the time, even with new parts from the manufacturer.