I have a 99 DOHC and had to replace the sender a bit ago.
Mine was located in the transmission just above the right (passenger) side catalytic converter. Because of the heat there is a flimsy heat shield around it--be carefull to slide it up the wiring harness or it will come apart!
If you jack the car up and get under it (use jack stands) on the passengers side it is hard to miss.
Hope this helps.
Old Klaw
Old Klaw