2002 Chevy Trailblazer p1345 code

Computer problem
2002 Chevy Trailblazer 6 cyl Four Wheel Drive Automatic

i went through a large water puddle and then the engine light came on. it started running real rough so took it to autozone to have the code read. p1345 came up. i know where the camshaft position sensor is but cannot find where the crankshaft positioning sensor is.
if you could please help with this i could save lots of money as i am unemployed at the time.
thank you,
craig