What does that thing run on?

That is some vehicle Pop has there.  It looks like it's part tractor, part old-timey automobile, and part monster truck.  (I take it that he and Shelly won't be using the element of surprise in their hunt for Mark.)  Meanwhile, Salty and Sour have discovered that Mark is gone (and Sour seems to have decided to change his shirt.  Maybe he wanted to be a lime.  Personally, I'm waiting for the limon shirt to make an appearance).  The genius of their little conversation is that it still makes sense even if you only use the bold letters.  (Idiot gone!  What?  See, you don't need all of those unnecessary filler words when three will do.  When times are tough, you have to always be looking for ways to cut back.)  And in another turn of events indicating that no one in this strip really has any idea what's going on, I think that Mark has just run into Sneaky (or his cousin Crafty) and is now moving through the swamp alone.  One has to wonder where Andy and the Jack Elrod Ball have wandered off to (and why the Ball is now with Salty and Sour), and why getting Mark out of the swamp suddenly turned into getting Mark out of the country.  Is he that great of a threat?  Just what can one unarmed man, who's more likely to deal the forces of evil a blow with his fist than with a gun, do?  (Should someone have called in the Marines, the Army, or the Coast Guard?)