I have had many of the M44A2 series and M44A3 series trucks. In my mind, without a doubt, the M35A3 is the superior ride with regards to safety, performance, and comfort. I particularly like: dual circuit brake system, the back up lights, seat belts, better/more comfortable seats, upgraded windshield wiper motor, heater in the cab (more efficient/better heat), Cat 3116 has way more power than the multi-fuel (although not as cool sounding), the truck was rebuilt/built in the 90s. One drawback that took me some getting used to is the looks. The hood, slanting backwards as it does, and often riveted together (unless you are lucky to find the fiberglass hood), is not very good looking. Some of the parts for the M35A3 are tough to find and expensive if you can find them. The tires are non-existent if you want recent, fresh rubber. I like to keep my trucks stock so that is important to me, but may be less important to others. Another drawback to the M35A3 is the top speed. It is even slower than an M35A2. They will do 50-52 MPH if you push them, but they drive more comfortably around 47 MPH.
With all that said, I would suggest you find one of the later 80s USAF M35A2s with the dual circuit brake system, which is more safe than the earlier brake system (and is the same that is in the M35A3). The M44 series has a classic mil-veh look that, IMO, is one of the sweetest looking trucks available. Parts are all over the place, and usually reasonably priced. And, that multifuel sound is nice.