Will a second battery help?

[jrwalte 10+ year member]

The replacement alts are typically going to be about the same amperage as your stock. in your case, the replacements are in the range of 75-160 amps. Big range. You may have to get the model off your existing alt and google it or call the manufacturer to get its amperage. Keep in mind, an alt of that age probably won't be giving out its rated amps anymore, either.