If you are trying to run a 100A alternator on a stock harness, YOU BETTER bypass the thing. First start by reading the MAD article:
Catalog
Now, you don't necessarily need to do so as they did here, but this article goes through the "why" of ammeter/ and bulkhead connector damage. You can buy new terminals, or you can drill them out and run larger wire through the connector body.
You can bypass the ammeter by running a direct FUSED wire from the battery direct to the alternator. FUSED
