RPM Sensor location and size

[Houston Texas]

Nate or DGraber, can you tell me how big it is?  I'm not sure where to
exactly look.  Is this sensor @ the front or rear of the engine?  Is it
near the bottom or top of the engine?  Is it near the Speedometer
sensor?  I have replaced that sensor.  Do I have to get under the car
for this operation?  Do I have to dismantle anything? How long should
the replacement process take?

Ameer says: it's located on top of the flywheel between engine and final
drive.  

Nate says: it's located on the block.   

Thanks listers for the much needed help.