Who all is running Dual Batties and who thinks it was worth the expense

[ugly_blazer]

[hijack] My alternator has 3 wires (1979 K20), what do each of these 3 wires do? [/hijack]

 

[dmanblazer]

The red one by itself goes to the junction block on the firewall next to the brake booster, the red one in the plug goes to the battery bolt on the starter and the brown one in the plug goes to the ignition.