I can mail or fax you the wiring diagram from 72.This was the first year a service manual was available. There are 2 dc systems. One for the running lights and brakes which start at the 7 way connector in the front. One for the interior lights and 12v
system which start at the univolt. The univolt generally was located in the rear curbside area. I also have some wiring info on the control panel area you mentioned. Send me a PM. Consider getting a 72 service manual from Secretarial Services in Ohio. There are service manual copies always on ebay.