bunk heater core
 

anyone know how much of a pain it is to do in a 04 columbia? i dont see it leaking but when i put the heat on in the bunk the smell of coolent is ureal.

Depends on what your level of "pain" is I guess, that's relative.

Passenger side , remove kick plate, behind there is a box with cover ,
remove 8 screws,
drain down coolant about 4 gals, remove hoses, at fire wall,
4 screws hold heater core in place, remove and pull out
(there may be some corner brackets too)

Good luck!

the front seems fine, its the rear one i think is shot.

There should be a panel/bed/bench that lifts up at the rear of cab to get to an access panel.