And as for the 336 / 337 Cessnas...
They have a fairly high wing loading, and can haul a whole bunch of junk. An old saying is, "If you can get it through the door, then the Skymaster can haul it."
Speed is fairly good.
There were some issues of overheating the rear engine, but I think most have been modded to correct that.
They were used in Vietnam as FACs - the designation was O-2.