Under the timing cover, driver's side, forward of the thermostat, driven off the timing belt.

On turbo engines anyway, you must remove the crankshaft pulley. A special tool is required to hold it in order to remove the very high torqued gland nut. In fact anothe special tool is highly recommended to loosen the nut. It is a socket welded to a bar that you snap a 3/4" breaker bar into. it is about 1' long which is good for a *few* extra newtons of torque.