This only applies to the EA82 alternator with an internal regulator. I've noticed some other people were interested in installing a second battery with an isolator. The white/red wire from the bottom of the T connector on the alternator is the one that needs to be connected to the E (excitation) terminal on the isolator. I've added a battery isolator to my 1986 Subaru GL-10 turbo as well as my '79 Datsun 510 and both are working well.