1965 valiant gauge cluster...again

The wire itself is a fusible link. Don't repalce it with a fuse unless you want no end of troubles; a fuse OK ONLY for temporary troubleshooting but you need to get a replacement fusible link.

If the dark blue wire with the fusible link tag has no juice at the end going into the bulkhead connector, then the whole car should be dead. So there must be some jury-rigged wiring around this into the dash if you are getting anything to work at all. That dark blue wire is the main power feed wire in and out of the car, and should have 12v on it all the time. Sounds like you need to start finding what is wired where.....

Do you have a wiring diagram? If not, please download one from mymopar.com . The fusible link is marked right on the diagram.