getting at the heater core 99 jimmy

I've managed to remove the dash and the obvious screws in the duct box enclosing the heater core. The threads I've read indicate removal of the top side of the assembly should give me acces to replace the core.

my problem is that there seem to be more places where the duct box is fastened. I can't remove the upper portion.

Does the AC gear under the hood need to be detachted from the fire wall to get at additional fasteners?

I thought I'd ask before I crossed that bridge.

It doesn't seem logical that it would be so difficult to replace the core.

Some help anyone.

jpm

Was your heater core leaking?

Yes, after a series of cooling system problems over the years. Got the coolant smell in the cab and gradually have developed a major leak. It's to a point now where I couldn't procrastinate any longer.