It is not a Terrible job, but you will hate the MB designers... you have to loosen the power steering pump, the A/C compressor and the alt to get the belts off. the a/c and PS can be loosened from above, the Alt has one bolt that is best accessed from below... three bolts hold each from moving. and each has a tensioner to loosen as well.
you are looking at about 3 to 4 hours to do it all... I would change the ps and A/C while you have them out.
enjoy!
John

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I is a bit of a PITA, but I don't know about 3-4 hours unless you run into a problem. Definitely replace all the belts if you are going to take the trouble to do this (the alternator/water pump belts are on the inside anyway). I think it took between 1 and 2 hours the first time I did it. The last time, I did it in a hotel parking lot in about 1/2 hour (barely got dirty). The trick is knowing all the tricks, like the best way to reach all the bolts. It also helps if you know nothing was over-tightened the last time. I also found that the OEM belts last longer than the "part store" brand belts, I don't believe the part store belts are actually the correct size.

If it's too much of a pain, just bring it to your indy, the labor should only be about $50.