Alternator on my previous coach with 330 Cat went out at 30,000 miles and 4 years. It actually died on I-5 in Oregon. I started the genset and charged the chassis batteries while driving. Ran it about an hour and then shut it down until I noticed the volts drop to a little above 12. Then started the genset again and charged them again. I did this all the way to the desert where I could then change it at my leisure. So at least you are stranded when the alternator goes.