Doug, thank you for the offer. I am going to talk to Marty about getting a new cab on Sunday, but if I decide not to go that route I would definetly like to get that piece off of your cab. Unfortunately, the rust goes all the way down to the bottom edge of the panel, which is of course the mirror image of the opposite side. If it was above the edge, I'd have been fine.
I am hopefully going to be working on the radiator core support tomorrow while I'm waiting to decide the fate of the cab, if so, I will try to post an update.
For your enjoyment, I have included some pictures of the old cab.