Vintage air uses the same thing, a black ABS block off plate. It looks just OK. If your going to really do up the firewall up 'right,' I would suggest a patch plate, welded and smoothed! I am very happy with my Vintage Air system and have zero experience with the old air unit. I am subscribed to several other threads that are in the processes of adding a rear air unit to their burb. I have a unit out of a 87 burb and will be installing it someday.
I have also purchased Vintage Air AC unit for my '57 truck. Should be installing it in the next month or so.
