18 gauge wire from battery

Just an FYI Of course we don't know anything about his stereo system. Amplifiers/ amperage draw on system ? Quality of components ? Install quality ? How long car can sit between usage ? Condition of the cars electrical system ? They were marginal when new. 40-60 amp alternators, mechanical voltage regulators, light gauge wiring, marginal connectors....
Here are some recommended electrical articles to help understand the electrical system on our Mopars and how to update/improve them.
Vintage Chrysler electrical repairs and updates
Vintage Chrysler electrical repairs and updates (part 2)
Improved Wiring for older Mopars
Fixing Dim Or Blinking Headlights - Quick Tech - Mopar Muscle Magazine
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