How bad is the leak in the air tank? Since it is only 45 miles away, I'd go to inspect it first and the plan to drive it back another day. I, personally, wouldn't drive it if it is leaking a lot of air. If you burn up the compressor, you will be in for a few hundred dollar replacement cost (a friend of mine tried to drive an M923a2 a good distance with a badly leaking air line, and he burned up the compressor). With that said, if you can swap it out, then I'd do it.
If you drive it home, I would suggest changing the fuel filters before you leave. Bring a good tool set, a jack, jackstands, a wooden block (for under the jack), a breaker bar and lug wrench, a couple of gallons of coolant, a few quarts of oil, and a five gallon can of fuel (the fuel gauges are notoriously unreliable). I also would add a good amount of diesel conditioner before you leave.