Locate a shop that can put a "load" on the alternator. Years ago we used a machine labeled a VAT 40. It had three leads, two to the posts on the battery and one inductive lead that clamped around the positive wire on the alternator. We would raise the idle to about 1500 rpm, turn a reostat knob to put a load on the alternator and verify it on a meter regarding AMP output. A 80 AMP would max out very close to 80 amps and likewise a 115 AMP would peg at just below 115 AMPS. Any alternator can be re wound at a rebuilder to produce more amperage and look physically the same.

__________________
81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.