340 exhaust manifold heat shield
For the demand we see (probably a post a week or more, with a dozen people chiming in also looking for one), you'd think suppliers would be pounding these things out considering how simple they are and what they get for them when they do turn up.
Victor, McCord and probably a slew of others made them in the past, so it's just a matter of one of them digging out the dies and stamping a run of a couple 1000 or so.
Never could understand how they could justify repopping the manifolds themselves, but the heat shields were too much effort...