Sal & Ed, I suppose you noticed, that this Thread is over a year old?
But one thing I've learned from this, after all these years, that AFTER 1976 & my just retired 2176B, Hi-Lo changed the Electrical System completely! Most, an improvement.
On it the Power goes from the Hitch Driver's side, up through the Center of the Upper Front Top Base/Shelf Below the Window & Cabinets & then distributes from there. Both 12 Amp and 115 Amp are ALL in the Upper Section, None in the Lower Section, except the Brakes, Battery & Power to the Hydraulic Pump (located on the floor in a covered 'step' with the Battery just behind the front was between the couch/storage on both sides). Not sure about the Travel Lighting from there and think it goes directly to the lights through the roof & too/from the Battery below, but the 115 Amp goes around to the Breaker Box in the Upper Cabinet over the Refrigerator on the Driver's side.
The 1976 was evidently the Last Year Without a Converter! It has both 12 Volt & separate 110 Volt Fixtures (only 110 Volt Outlets). So, the Battery has to be good, or kept charged with a Float Charger or be prepared to use Jumper Cables. At least, other than removing anything stored on top of the lid, you had access to both the Pump & Battery. The Hitch area is Just a Hitch with a small Shelf for the Propane Bottles & No Storage. I.E., No Manual Pump Jack to lift the Top either. The PO evidently added some 12 Ga Romex with an Exterior Outlet wired to the Pump a Jumper Cable connection For lifting. Never used it myself.