On the M119, it's on the passenger side (LHD car) near the front of the engine, stuck through the side of the block just below the level of the crankshaft. It's right next to the oil pressure sender.

I'm told that you have to drop the oil pan out of the car to change it. That could entail a bit of work because on some cars (like my S420) you have to hoist the front of the engine a bit to get at the front three oil pan screws. Since you already have the motor lifted-up, you might as well do motor mounts too!

__________________
"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles