You’re looking at grill slats, I think, (PN 454-170) not the outer shell. That’s the hard-to-get item.
Slats in original TDs were originally painted. Hence the zinc plating.
I know looking at the diagram on the Moss page it looks like you’re buying the outer shell (I had to look at it carefully again), but there is a reason that PN 454-757 is “radiator shell” and it’s “unavailable.”
Hence the prevalence of $700 and $800 used rad shells on the ebay, with many bidders.