[Mister Pontiac]

I think the bigger question is, do you have A/C or not?

Without A/C, the swap is easy and straightforward. If I remember correctly, there are only 4 studs that go thru the firewall holding the heater core box under the dash. I was able to remove it without pulling the fender/inner fender.

With A/C, it takes a little more work since it's hard (almost impossible) to get to one of the nuts on the engine compartment side without pulling the fender & inner fender. Year's ago, I went so far as to take a hole saw to the inner fender to access the nut. Today I would simply pull the fender/inner fender.

Hope that helps.