1972 Duster. Are firewalls different for heater/defroster models versus A/C ?

Agreed, Classic Air's plate looks like garbage, just a smaller single hole, why do they even bother.

Can I swap any a-body a/c setup into my big block 67?

I understand I'd have to make the fan motor hole larger, and add a few holes for the lines.

The pics I took are from a 67 383 with what appears to be a factory air setup.

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