[markeb01]

I believe your assumptions are correct. These junction blocks may have a different appearance from the 1966, but following are a few diagrams from the 1960 Chevy Accessories Installation Manual that shows the factory had purposeful connections to the open terminals on the stock fuse panel. Some of these accessories included a radio, spotlight(s), cigarette lighter, glove box light, turn signals, windshield washers, heater, and lighted compass. For some accessories an auxiliary fuse panel was even added to the stock fuse panel: