Well that got involved fast...
First was just picking at the A-pillars. Then it was using a Dremel wire wheel on a few rust areas underneath the driver's A-pillar. Then it was screwdriver and hammer time on the rest of the rig and pulling out all the old sealant. I wasn't going to do that, at first, but once I got into the A-pillars it was obvious that the old stuff wasn't quite cutting it any more.
Underneath the A-pillar, after some wire wheeling and Ospho treatment. I re-sanded and re-Ospho'd this after this photo. There's nothing poking through, just some pitting here, much of which will be covered by new seam sealer. I'll also fill in some of the deeper pits with some JBWeld.
Passenger side wasn't nearly as bad.
And then cleaned out rain gutter channels. This was the better part of an afternoon. The original stuff was still pliable but cracking in a few areas. I will clean this up a little better before using some 3M 08307 self-leveling.
And the other side.
And here's where one of the spot welds has started taking on rust. Note that there was zero indication of a problem under the sealer. In fact, there wasn't even any cracking under it.
I also found some surface rust right at the edge of the roof seam in a few other areas, where sealant was packed in tight but somehow got water underneath. I've coated the whole thing with Ospho, will let that cure up overnight, reactivate, and then wash it with a wet rag and some soap.
I'm also doing this in two parts. The first part is to seal the A-pillars, front and back, along with the section up above the front doors with some high-body seam sealer (3M Drip Chek) right at the seam. Then, I'll get the rest of the drip rail with the self-leveling seam sealer, which fills the whole channel. I haven't decided if I'll do the self-leveling stuff on top of the high-body sealer, will research. I'll get some rattle can primer and color to match, and then that should address at least a good portion of my water issue.