Here is a picture of my power bay.
Power switch, just left of center, black cable into bottom is shore power , grey cable is from generator. When generator runs , switch automatically switches to that power source.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.