is the tnx open on the bottom like this picture shows if so would it get messed up by dirt and stuff geting into that?

http://www.rcpics.net/view_single.php?medid=37329&PHPSESSID=d6ac22de525ec0d02ca474d7f564cf79

What do you see that the dirt might get into?
Brian

that big thing that sticks out

There are many monster trucks that do not use a "pan" type chassis and have gone to a ladder type chassis for stiffness. Two that come to mind are the Savage and Warhead. Those that still use a pan type chassis are like the TNX, such as the Titan and Revo.

Having a sealed pan chassis would not keep dirt out and would hold dirt in which would be much worse then allowing it to fall through the holes in the chassis.