I can't answer on the maintenance costs. Certainly if it's important, I can get some information on that.
In terms of age, I flew the Buffalo when I was fairly young, so that goes back a long time. The aircraft is the sixties vintage. The Hercules, depending on what airframe, because we've had a number of models.... Certainly these aircraft are really old, but they are still very capable, and that's because of that higher maintenance cost to make sure they are safe and effective.