Hi again,
So the 3.0l engine in x250 Fiat I believe can only be an Iveco one Sofim F1CE048ID with M40 gearbox and if you head to the guides section, one of the training manuals(I believe the second one has very extensive and valuable information about the Engine, the factory air suspension, auxiliary heaters etc. ) I believe my alternator was 180amps, but I'm unsure what yours would be if it's build as a motorhome from the get go(mine was an ambulance so it might also not be standard). I believe you will have a fairly easy time taking a look underneath and seeing the amperage of your alternator as it's really accessible so just go underneath and take a look.
For future reference if someone is reading this and wondering if they can do the work themselves.
Disclaimer: the following is not a guide, just an observation and collection of information from the internet by someone who is trying to learn more about their vehicle and are relating Fiat x250 3.0l 180bhp Iveco engine with a manual gearbox.
The alternator and alternator belt can be seen on the Rear Right side of the engine and are fairly easy to identify. The alternato belt tension pulley is visible and accessible but very difficult to access(pray you have small and strong hands as I barely managed to fit my hand to do the job) I personally could not find a way to replace the alternator tension pulley(at least it looked in a really good state in my case) without any special equipment allowing me to drop the engine from it's mounts to get a better access, but the alternator belt can be replaced with just bottom access and sufficient strength and time.
The AC belt is positioned on the outside of the alternator belt and is clearly visible and accessible from the bottom Right side, middle to front of the engine and the ac compressor is easy to identify at the front right of the engine. The guide pulley for the AC belt is not a tension one, but quite easy to replace, however, that makes the belt difficult to replace without the appropriate tools. There are some videos out there showing how to perform that change of the AC belt by temporary taking the AC compressor off it's mounting points and slightly tilting it, but that proved difficult in my case and I left it and paid someone to install the belt.
Bear in mind that I am not a mechanic so no need to ask me about more specifics as I have nothing more to add to this. I will also, appreciate if someone more knowledgeable has an idea of how to tackle the problems that I have encountered in a DIY environment for the sake of getting that information out there and I don't get stuck on it again in 3-4 years when I change the belts again.
I hope the information was useful.