Short to ground. Please help!

When I bought it, the altnator was hooked up to the bulkhead as it should be, a heavy gauge black wire. The power line fusible link was melted, I replaced the fusible link and disconnected the altnator, hooked everything else up as it was. No issues with the fusible link since.
Pay close attention to @Mattax post. He will save ya! He has forgotten more than most of us know On electrical gremlins issues.