On the subject of the M880s and Dodge truck in general, I personally love them and while they do have their quirks, they are easily overcome. Everyone has their preference as to which brand or model is "best" but what it boils down to is what is best for them. I have been a Mopar guy all my life and I stick with what I know. I have also been a mechanic, restorer and fabricator for a long time so I've gotten a pretty good handle on what the other makes have to offer and I still stick with my Mopars.
On the M880 specifically, they are good trucks for sure but as I said, they do have their quirks. As much as I love Dodge trucks, I do not like the full time 4WD system used from '75 ('74 for the Ramcharger) to '79. The D44 with it's odd front bearings is weaker than the more conventional spindle setup used in prior and later years. The NP203 is a good strong transfer case and part time conversion kits are available but are generally not worth the money it costs as there is little to gain. Like Kenny said, the M880s are cheap and simple to operate and maintain as are any of the Dodge trucks from that era. I agree that it shouldn't be very hard to find someone willing to swap an M880 for a M1009 since Dodge has ever been the underdog and GM vehicles are always popular. If an M880 is not available, you can always go with a civilian version and militarize it to your liking which is what I am slowly doing with my '88 Ramcharger. To me there is no better vehicle on the planet. There are more powerful trucks and some that are better at specific things but for my uses a Ramcharger is ideal and the few things that fall short, like the 1/2 ton axles, get replaced with better or stronger parts. If you decide to go with M880 or similar '72-'93 Dodge truck there is plenty of info here on the military versions and tons more info on the stock civilian models over at RamchargerCentral.com