Astro van voltage and fusible links

I have a 1993 Astro Van AWD 4.3 vin W.
Over the past few weeks my voltage gauge has been dropping after the van has warmed up. A few times it dropped enough
to make the battery light come on. I checked my connections and switched the battery with a newer one from my truck but nothing changed. So I had my alternator rebuilt. So far the battery light hasn't came on but the needle still drops.     I checked the voltage with a meter at the battery. Under load at idle it would drop as low as 12.4v. While the van was running I checked the fusible links at the harness behind the battery and noticed that the black one was very hot.     Does anyone know what the black fusible link connects to and can this cause a voltage drop? Thanks, Stephen
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