Coolant leak - Heater Core??

[chaingun]

Have 99 F250 Powerstroke 4X4 and just developed a heater core leak. How do you go about replacing it? Do you have to dismantle the dash or can it be done from the engine side? Any help wold be great!
Thanks, Ted
Well I sucked it up and bought a year sub to Mitchell on line manual and now I know how to get to it... but is this the problem? I had a slight coolant leak from the passenger side engine compartment in the area were a heater hose would drip on the ground. Could not determine were it was coming from but the heater hoses looked OK. Today I have a faint odor of coolant coming from ac vents. No leakage in cab under core. Can the core be leaking enough to smell it but not enough to drip into the cab area? No noticeable exterior leakage today driving about eight miles. Any thoughts?
Thanks again, Ted