D6 9u electric starter

That's a really crappy picture of the s/n. Those cell phone cameras are the pits.
1115556 is a starter solenoid for a Delco 50MT starter.

The auxiliary solenoid makes the ignition switch last a lot longer. Most of them aren't really up to the amperage that big solenoid requires

Thanks for the information. Has anyone put these on the 9u before? Some of the bolts to bolt it to the housing you can't get on them to tighten them really at all.

For the bolt against the block use the smaller headed bolt style which takes a twelve point socket. Them style bolts have a name but can't remember what they are called. You can easily tighten them with a long extension and a swivel on the socket.

12 point flange head cap screw is what I think you're talking about.

I believe you are right. The fastener store will know if you describe it.

The auxiliary solenoid makes the ignition switch last a lot longer. Most of them aren't really up to the amperage that big solenoid requires