I've looked on our '02 Monty and unless I'm blind can't see that there is a drain anywhere on the radiator for the coolant. Don't really wanna pull hoses, but if I have to then I will. Gonna be getting me a Chilton book this weekend to help me out on some of this stuff, but thought I'd ask here too

*edit* forgot to say I have the 3400.

might have just found my answer, but will still read any help

 

A petcock should be located at the lower driver side corner on the back side of the radiator. It's hard to see because the air dam hides it. You will probably need to remove the air dam to get to it.