M112 Alternator on OM603?
 

There's two 3.2L M112 Mercs at the yard right now I need an alternator for the SDL, are the mounting points on the OM603 and M112 alternator the same? I still have the old alternator so I can switch pulleys if need be.

It depends on what year and what chassis it came from. All M112 or m113 alternators will bolt up to your 603 but the later ones (w203 w211 R230 etc) use a digitally controlled voltage regulator which needs to be swapped out for a conventional B+ D+ VR. Also if you're looking at anything over 90a you need to use a over running pulley when mounting it to the diesel. Otherwise it'll murder your tensioner and damper.

On my 603 I'm using a 150a alternator from an R230.

They're from a 2000 E320 and a 2002 Ml320, I'll also take the alternator harness as well.

I never understood the over running pulley, how do I get one?

The overrunning pulley is absolutely required if you're running the high amp alternator. The INA one for the VW will fit. You'll need a special tool to install it. I have a 143A in my SD from a '94 S420. The inertia from the heavy rotor will quickly tear up your tensioner and damper as mentioned above.

https://youtu.be/DGI9XLuhaYY

https://imgur.com/70bYUf1

https://imgur.com/s5K4KqI

Which model VW do I buy it from?

Any Jetta or Golf. They're all the same. They're about $20 all over the Internet, do a search.

Ok