Well, easy... those plastic rivets can be a bit of a pain to remove, they also tend to break. But aside from that, it's not too hard to remove/replace. I am changing my '84 from the bumperpad-style to the GT-style, same as you. No, you don't need to switch the honeycomb piece, they are both the same. Just take your time, and save as many fasteners as you can.
Posts: 1926 From: Niagara, Ontario, Canada Registered: Feb 2006
When changing from a bumper pad to an aero style fascia, you'll need to change the fenderwell liners, also. If you're just replacing the fascia, only the rear piece of the liner needs be replaced. If you're also installing aero rockers, you'll need to swap out the front portion, too.