Need some electrical help with my ‘68 Plymouth Valiant 100

4mulas said
Electrical systems can sometimes be tricky but mostly this sounds to me like it may be a bad grounding issue. Check all your grounds for contact and tightm]ness. Also check all your positive connections at the battery, starter solenoid, alternator, ballast, bulkhead connector, and ammeter. You problem likely lies within these areas

Thank you I will for sure check these out. So another thing, I have ordered an original ‘68 valiant manual, but it won’t be here for probably about a week or so. I’m assuming it will have a diagram showing all of the electrical? Is there a diagram online that I could check out now so I can try to get a head start?