Here is the schematic for '78: http://www.fordification.net/tech/im...ster_3of10.png

Basically you have the bat pos cable, fuse-able link & main alt hot going to the radiator side of the starter solenoid. The starter cable to the other side.

Then you have the two sm posts. The "S" post is for the start signal form the ing switch. The "I" post is for the hot while cranking signal out to the coil.

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