GM alternator conversion
 

I just finished converting my w108 to a newer GM alternator. My old alternator was ok without any load, but as soon as I turned on the lights or A/C the voltage dropped to battery level. I replaced the voltage regulator, but it only helped a little.
Instead of rebuilding the original alternator I bought a new one for a GM truck (thanks for the tip Al) from a large online auto parts website. I also bought a wire connector pigtail for it, and replaced the serpentine belt pulley to one for a V-belt. Luckily the one we use to convert Ford alternators for old Fiats fit perfectly.
Installation took less than 2 hours, it basically bolts on. I flipped the upper mount over so it reaches toward the back of the new alternator and I had to bend the dipstick tube slightly to gain more clearance for the output stud.

Voltage is 13.6-14.0 volts even with all accessories running.

Did you go with a CS-130? I love those alternators and put them on all my old project cars. They are cheap, durable, and put out a ton of power. Plus they are simple to mount and even easier to wire up.

What is the amp rating for the new alternator. I had mine replaced with a 90 or 95 amp alternator. on my 72 4.5.

The CS-130 alternators are generally 105 amps.

This one is a GM GM "DR44G", I believe 105 amp. They came on 2005-ish GM trucks. The wire connector is Airtex p/n 1p1153.

105 amps is a healthy number. You should be able to run some fog/driving lights as well without any sign of flicker.

I really want to do this on my 280C, two voltage regulators later its time for a new alternator.

I did this conversion last year on a 1973 280 (W114) with an M110 and really pleased with the results. Installed a 135 amp GM alternator and IMHO it's made a huge difference!

I posted (somewhat) step by step instructions here:

http://www.peachparts.com/shopforum/vintage-mercedes/357901-replacing-55-amp-alternator-m110-engine.html

Purposely parked the thing outside in February of this year when it was -6 Degrees F, let it sit outside all day and then started it with the lights, fan and radio on as I cranked it over. Fired up on the first crank and the voltmeter sat at a steady 14.6 volts.

Worked so well I'm going to do the same conversion next week on my "other" European vehicle.