I swapped a 3G in and now the belt for the vacuum pump gets tight before the alternator belt does. How does this make sense?

 

The vac pump can be adjusted separately, there a 2 bolts on the pump mount, they take a 10mm wrench.

 

what he said.
also, i found that a 130a 3g unit will often slip the belt right after startup, requiring more belt tension. i found an easy trick to tension the belt. i bolted a large nut (1"+ hex) to the alternator adjusting bracket then used a c-clamp to pull the alternator upward toward it before tightening the adjusting bolt. much more effective than a prybar or crecent wrench trying to pull the alternator up while tightening with one hand.

 

Thanks. I was able to adjust it and everything looks pretty good