I've got a few areas that have minor body seam rust and two areas that
have significant body seam rust.

Where the rust is minor, it appears that that the filler or caulk that
is between the body panels hardened and became brittle, cracking the
paint and allowing water in.

Where the rust is more advanced (the seams under both front doors) I
think the paint merely cracked sooner.

Does anyone have successful experience treating this type of rust at the
seam?  This doesn't seem like a good candidate for cut'n'patch.

I have electronic pictures of the rust if that'll help.

Thanks,
...Markus

engineless '87 Syncro