Glad you resolved your starter problem.....and hey you became more intimate with your coach starter systems as a side benefit too.
Now after installing this third chassis battery, check and make sure when you are on shore power that it is charging properly. Place a voltmeter across the chassis battery with engine off; no loads and shore power on for a minimum 5 minutes and you should see 13.1 volts or higher. Of course then you could also check with generator on as 120vac source and then try with only engine running to make sure all systems are charging that chassis battery. Enjoy.
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