It could be your water pump. Prior to 2005 Cat had a grease fitting on them that people never greased so there were a few water pumps that went bad. On our 2005 Fleetwood Excursion with a C7, they went with a permanently greased water pump. I keep wondering how long they will last. Ours has about 44,000 miles. Last year I did check and I could still get the parts to change it back so that I could grease it if this one went bad.
My alternator is doing fine, I think...... Sometimes on startup, it will read 16 volts and a warning light will come on for about a minute. I did a bit of reading on these also. While the alternator is available, it's not available everywhere. It's not just a standard 160A altnernator, there's something else in it that's needed to make the MH electical system work correctly. I was thinking of buying a spare, but that's weight and they aren't cheap. The MH has two years left on the service agreement from the previous owner, so I'll let them buy it if it goes bad. If you don't have a service agreement, you might consider buying a spare - but you can only carry so many spares.
Here's the info on the alternator and there were a lot of different prices out there, so shop around. All of the places I looked at were standard Leece Neville distributors.
Leece Neville
Model A0012824LC
Amps 160
Volts 14
Date 200407
Sales No. 2824LC
Manufactured in the USA by Prestolite Electric, Inc.
There is also a heavier duty model make for fire trucks and ambulances, but it was about 30% more.
Bill