That picture is a little confusing since the wires are not individually numbered or shown in the correct scale to size. I see four wires coming out of the harness there. Is that part of a M151 diagram? If so what manual so I can get a better look at it. Aren't you going with a Mercedes alternator? All internally regulated alternators will have either 1, 2 or 3 wires. One wire alternators are a US thing only I believe. 2 wire will be a charging wire to the battery which will be a larger wire and a field wire from a switched ignition source. 3 wire will usually be the two wires mentioned before plus a larger ground wire from the alternator to the engine block or body.
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone