Seriously Need Help

wow Mattox ! more info Great !! , ok after checking all wire connections. I load tested the battery ( it’s one of those battery inside battery maintenance free vintage look alike) it come in at just over 300cca and is 9 years old. I put 10 amp charge on it for 2 hours as paperwork recommendations . seems to hold 13 volts and starts the car just fine. No upgrades at all to electrical system except the electric voltage regulator. Heated floor garaged car thats why battery has lasted so long. After checking wires and charging battery, alternator seems to have calmed down now, but ..... now the temp guage is not working at all ...uggh .. this car has a demon !!! Maybe its a dodge demon and not a 64 cuda ha ha.. do you think at this point I should replace the battery. as the paper work shows that battery had 640 cca new. I have an old school mechanic helping me ( he is my age 68yrs) and he is at whits end too. we did try putting a different battery in it when we were looking for the amp meter problem and it didn’t help. Gosh I hope some wiring isn’t now damaged somewhere . No wires felt hot while checking things. Going to try to chase down the temp gauge problem now. Man I hate theses electrical problems.