The sensor I believe you're referring to is the speed sensor.
I'm not sure what the name of what that part is, but you are talking about what the shaft runs though to the right of that sensor/gear correct?
Blue '04 Redline Best ET Gas:firstname.lastname@example.org, E85:13.94 @ 109.17
289 WHP/262 WTQ on E85
K&N CAI, HP Tuned, zzp heat exchanger, 2.8, 80's, zzp header/dp, GMPP clutch, front and rear TTR mounts, Nitto Neogens, Hawk Pads, irotor cross drilled/slotted rotors.
Boost gauge/ladder tach w/o amishland- courtesy Spike50002