Thank you a million, onehundred80! That's *exactly* what I needed!

Those clips look entirely different from mine - the tops of mine aren't curved and I'm missing what appears to be a rubber shim between the clip and the radiator. Weirdly the service manual doesn't show that shim or the curved top... the illustration in the original '04 service manual looks almost exactly like my clips and not yours, except mine fall out, so yours are clearly superior.

Any part numbers off of those clips?

I'll take pictures of my setup and part numbers when I get home on Friday, just for a cross-reference in case anyone else has a similar issue.

For now, I'll probably just make an improvised version of that rubber shim and call it good, since that will probably fix my problem perfectly.