early model starter connections

[ScHpAnKy]

which post is reference/ignition?
also which one is pos/neg and do I need a 4th connection? I imagine that the one with a grounding strap is ground and the the one furthest from the starter is pos?

This is for a '86 325e, here's a pic of what I have now minus reference since I can't find which is which

[CW325]

im pretty sure the black and red wire go on the same connection (the connection on the right)