1979 Other Lincoln Models car seems to have short but cant l

I have a 1979 Lincoln Versailles. We replaced the alternator about 6 months back. Now recently we replaced the cable running from the alternator to the cellunoid positive. It is a fusible link that was causing the battery not to be recharged and the ALT light came on. Now our old battery(which we had tested, they claim it was good) was draining if we left the Positive terminal on the battery. We did the test with a light meter on the negative and pulled the fuses under the dash one by one to isolate the short, but none turned the light off(indicating the path of the short). Then it seemed our battery was swelling and bleeding and directly after driving you could actually hear the positive terminal sizzling. So we replaced the battery and battery cables. Now the battery has again drained after a night or two. Is there a way the cable we replaced could somehow be overchargind the battery while driving and draining it at night? If the short is pre fuse box what options do I have past the cellunoid?