Battery Boost Solenoid Location? - 2007 Gulfstream Class C

I have a 2007 Gulfstream C on a Ford 450 chassis. Noticed on one diagram that there is an AUX. start solenoid and the other diagram it is called a relay. There is only one on each diagram. Could it be that they are referring to a solenoid on the starter and there is no Aux. start solenoid? Maybe your house batteries are dead? You should know where the BOOST SWITCH is at. Let me know what you find, for I want to know also.