72 demon 340 common under dash wiring issue for no start, no power
Above posts are right. Read the MAD article, here
http://www.madelectrical.com/electricaltech/amp-gauges.shtml
You surely have damage and problems at the bulkhead connector. The diagram from the above article:
is a great overview and simplified diagram of the main primary power. Following from the starter relay, through the fuse link, ALL power into the interior goes through the red wire / fuse link and through the BULKHEAD connector.
You can buy "Packard 56" terminals used in those connectors. I got mine at 'clips and fasteners'
http://www.clipsandfasteners.com/Packard_56_Series_Male_16_14_Gauge_Terminals_GM_p/w31c030.htm
When you order the female, PAY ATTENTION, as one type they sell is wrong. Take a very very good look at your old ones, make sure the new looks exactly the same