'95 Islander Battery Isolator

['84_241_Offshore]

I am in the process of replacing the Twin '95 175 Johnsons w/ '05 Evinrude 175's.
Question on the wiring of the Battery Isolator. I failed to take note of how the Isolator was connected.
There are 4 wires going to the Isolator as illustrated in the attachment, but I'm not sure on where they were connected to the engines.
Any insight would be appreciated.

 

[Geaux_Army]

Can you take a picture of where your isolator is mounted. I recently purchased the same boat. The boat only was rigged with two batteries not three. So trying to figure out how to connect 3rd house battery.