Welcome and congratulations CABass!
We have the main Phoenix owners manual for our 2007 and it is not worth the paper it is printed on. So you are not missing anything. Ours is a black-&-white copy of a copy many times over, so bad that it is hard to make out. Being our first fully-featured motor home, I felt a bit in the blind, but I quickly got up to speed without the help of the manual. BTW: Our manual is generic, not model specific.
Does your 2004 2350 have the integrated spare tire like our 2007 2350?
CLICK HERE to see ours. I have gathered that our rear wall and main entry door which is used to this day, was a mid year 2004 production change. So you either have the older design or the current-day design.
Also, does your 2350 have a couch in a slide out? If no slide out, what is there, a couch or a dinette?
Our rigs will be very similar from a mechanical perspective. The primary differences will be that you have one battery mounted on the driver side. We have two batteries mounted below the floor on the passenger side along with a whole house inverter. They were introduced mid-year 2006.
We replaced our barrel chair with a 3rd matching captain seat that utilizes the same mounting pedestal and seat belts. The upgrade has been exceptional. You might want to consider doing the same.
If we owned a 2004, I would check the power converter to see if it has a setting for AGM batteries. If so, I would remove the single 12V battery and battery tray and stuff two-6V AGM batteries in there for massive power reserves for the house. Just make sure you can get two 6V batteries in there. If not, you can surely get two 12V AGMs inside. But two 6V AGMs will perform better than two 12V AGMs. Sam's Club sells both 6V AGM and 12V AGM, priced affordably. AGM batteries do not require any kind of maintenance. You install them, and "X" years later, you replace them. So a battery tray has no value with AGM technology.
Look under the rear of your coach and see if you have a rear stabilizer bar mounted rearward of the rear axle. It won't have one unless a previous owner added one later. If no rear stabilizer bar, you will MOST DEFINITELY want to install a heavy duty rear stabilizer bar. Helwig is an affordable brand. You will also want to replace your wimpy thin front stabilizer bar with worn-out end grommets, with a heavy duty front Helwig bar. If your shocks are tired, consider replacing them with heavy duty Bilsteins. Between the 3 upgrades, your rig will handle so much better on the open road and mountainous scenic byways. Installing everything yourself will make the upgrades very affordable. For both safety and driving comfort, you can't beat the upgrades.
Again, congratulations!