Alternator replacement on Cat C7, Freightliner XC chassis

I have the same unit, it is way more accessible than the other bedroom areas that have the bed in the slide. Be happy that is what you have.
My alternator is a Leece Neville LN2824LC , it is an internal regulator. If you google that number you can get to the website for it and it has good pics and info. There is always a chance a p/o has changed it out as there are Delco units that fit also up you can start there.
The suggestions of checking output elsewhere are a good idea before you start pulling things apart.
Bob