You need to bleed the ASR pump separately on W124 models with ASR. But you do not need to do anything special on a car withou ASR - just evacuate the MC reservoir, refill, and bleed all four calipers. The "SP" port only exists on models with ASR. As mentioned above, I very strongly recommend pressure bleeding, and NOT using a vacuum method. I don't believe the vacuum method works at all on cars with ABS, due to valving in the pump assembly... pressure is required. You can use the "pump the pedal" method, just don't press the pedal past halfway down on each stroke.
Factory procedure for bleeding the brakes (through 1993) :
http://www.ps2cho.net/downloads/MB%20CD/W124/w124CD1/Program/Maintenance/My81/4280.pdf
Factory procedure for bleeding the brakes (from 1994) :
http://www.ps2cho.net/downloads/MB%20CD/W124/w124CD1/Program/Maintenance/94_95/4280.pdf
If you don't have a pressure bleeder, you can either make one, or buy the Motive Euro pressure bleeder for $50. It pays for itself with one use. Don't forget to use DOT4 fluid... Valvoline Synthetic is the best bang for the buck, IMO, and commonly available at your local McParts. I prefer Ate SuperBlue or Type 200 if available (but it costs almost twice as much).
