I'm not sure the proper term, I'd call it the lower cowl? I don't see anything that looks close in the AMD catalog, you'll probably have to find a used one and cut it out. If you're in CA (like your tag says) ot even NC you should be able to find a donor, for that particular piece I'd bet it would be the same for Dodge or Plymouth and even 4 doors? Maybe someone who knows more will chime in. I'd measure yours up close and head out to the junk yards, I'd bet that 71-74 would fit and I'd be looking at 75-76 too, if you happen to stumble across them. I keep a couple pics on my phone so I don't need to rely on my memory, and write the measurements down. The worst part will be tearing it apart enough to see, but once you find one the yard might even cut it out for you- if not it's time for a hole saw in a cordless drill and a battery sawzall!