As I recall, there are four posts on the solenoid. Two are for heavy loads and two for the "light" switching loads. The solenoid, as you know is just a kind of relay-like switch.

The starter wire key switch goes to one of the low load ("light") connectors; and the other is a ground line.

The high voltage connectors go to the starter with the battery or alterator post; and I think the otherone goes to the other connector.

I don't thing there's any polarity issue as to which is which.