I had a 1956 550 GMC with an Olds block V8 which was my first 18 wheeler. It had a wire from the from the starter soleniod, to the coil. The reason I remember it is because I left it off once when I rebuilt the starter and it took a while to figure out my cold starting problems was low voltage at the coil. My maintenance manual only goes through 500 and I need to buy a 550 up manual because I am building one.
