Recently did the pads on a 1990 126 chassis. Without a doubt, the easiest brake pad setup I've ever seen. Not sure how different your model would be from mine, but I did end up with a bit of a project.

On the last (RF) caliper, while pushing the piston back into the caliper, I noticed a very small amolunt of moisture. Uh-oh. Yup, brake fluid began seeping past the piston seal. Ordered a new (not rebuilt) unit from AutoZone and was very pleased to find it not only was the correct Bendix unit, but also had the Mercedes emblem on the casting. Biggest problem I had was bleeding the system. My power bleeder wouldn't work because there are two breathers on the top of the master cylinder reservoir that prevented enough pressure to effectively bleed. I always suck out all the fluid I can from the reservoir before replacing pads since it's 'old' fluid anyway, and insures fluid won't overfill.

Have fun!