Problem finding electrical short

Hey guys,

I have a short in my wiring harness in my 68 Cuda. New M&H wiring harness. modified for electronic ignition and ammeter replaced with voltmeter in the guage cluster. Ammeter wires were butt connected and soldered. Short is present in the red wire that runs from main post of the starter relay to the bulkhead connector. I have removed the fuses one by one, disconnected the rear tail lamp harness, the dash cluster wiring, ignition switch, headlamp switch, flasher units and flasher switch, wiper switch, console harness, and the door switches. Also dropped the fuse panel and didn't see anything wrong there either. The battery is fully charged and load tested. Everything was working fine and suddenly, the interior lights started flickering. . I can see most of the harness but there doesn't seem to be any cuts or damage to it..
Any help would be greatly appreciated. Thanks guys.