As different year models have different alternators, yours may be at max output. Mercedes realized that the small(65A) that was used until 1990 didn't have enough power. They started using the 80A in 1990. I always recommend the later, & stronger one as a replacement. All that is needed to install the stronger one is the later harness. It costs only $50-$60. The old harness can be modified but requires heavy duty crimpimg tool & resoldering.

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