Alternator Brackets: 20 Valve
These are the brackets from a 1991 200 20V Sedan and Avant for comparison:
Alt: Edge of photo on Left. A/C on right.
Closer photo of the A/C bracket.
Notice the star wheel adjuster has a outer edge a bigger wrench can fit on. Use this to tension.
Use the smaller 13mm? bolt to "hold" the tension setting. It can strip EASY!