The simplest way to check an alternator for parasitic drain is to disconnect the main charging wire for a few days. The connector will be hot, so insulate the terminal with a few wraps of tape. If the battery stays hot, you've found your drain- - - -the alternator rectifier diodes.
If you're running the original-equipment alternator, the remote regulator can cause a battery drain also. If disconnecting the big lead at the alternator doesn't help, try disconnecting the 4-wire plug at the regulator.
Jerry