What exactly do you mean when you say interconnection? If just hooking finder to motor with installed US2 transducer all you need is a Finder model specific adapter cable abut 35.00. If you are wanting to use finder and motor together for following break lines and tracks then you need the IPilot Link system( or in other words have the finder telling motor what to do.) and for that to work you would also need a card from Lakemaster that had your lake on it.
Proud Member of Team Geezer
Charlie Weaver USN/ENC 1965-1979