I have 2 Furuno finders ones an 10 pin which is connected to a B60 a nearly flushmount thru hull ducer. The other unit I switchout is a 8 pin, I'm considering splicing a Y into it several inches down from the 10 pin connect without cutting the cable just peel insul back and solder like colors. Will the 2 left over not be needed on the 8 pin?