[SilverMiner]

Excellent, thanks so much for the response. I am following your diagram as faithfully as possible - I even bought the exact same junction block and am making the connections on the block in the order as shown in the diagram. Not sure if that makes any difference, but I find it satisfying to precisely follow well engineered plans. Only my j-block showed up black, dang it.

I will electrically isolate (but not completely remove) the original sensing wiring that ran back from the alternator along the valve cover to the junction in the factory harness and replace it with a 12ga. wire back to the junction block. That is what I assumed the diagram intended, but I thought it worthwhile to double check. There will still be factory systems such as the heater fan, dash lighting, power door locks and power rear window which will not be serviced through the new j-block, and I wasn't sure if those loads needed to be sensed by the alternator.

The loads distributed from the junction block will include minor draws such as supplementary charging points, aux. gauge lighting and other misc. systems in the cab off a relay triggered by key on. The major draws will be headlight and aux. LED light relays and a 250W stereo amplifier always hot off the j-block.