Engine will not Start... Trouble shooting help requested

Thanks guys......

I pulled the chassis battery out and installed my Jeep battery and the MH started up right away. I removed the Jeep battery.

I cleaned up the terminals and posts of the old chassis battery and installed it. They actually looked good, but apparently, that was the problem. All works fine and alternator is charging chassis and house battery at 14.4 volts

My chassis battery is almost 5 years old and I should think about replacement. Any thoughts on replacement battery size and brand?