RV Repair: Motorhome heater Core replacement, heater core replacement, winnebago journey

Question
How difficult is heater core replacement on my 2002 Winnebago Journey Model 32 T.  The unit appears to be mounted on the outside firewall and fairly accessible.  Are there hidden gremlins that I am not seeing?

Answer
Although I ask that "specfic model" questions not be asked, I will guess that if the unit is mounted on the firewall like most class a's, it should not be much of a problem replacing it.  My only question would be why did a heater core on a 2 year old coach go bad already? You might want to talk to Winnebago about this one.