For anyone that wants to know. Being I was use to a simple batter isolator that only connected the chassis battery with the coach batteries when the ignition switch was on, I was surprised that was a better way. Also connect the chassis battery with the coach batteries when on shore power. Here is how it done.
I don't know where they mounted this unit on all models but on my Lexington is under the driver's seat. So Lexington owners, be careful of metal objects you stuff under the seats! An inverter is under the passenger's seat. The isolator relay is in a box next to the coach batteries. Along with fuses for the slide outs. This is where my Lexington stuff is located, I don't know abot class C & class A models.