The exact same style were in my 2002 22 Cruiser (which was built in late 2001, so not in the big production atmosphere). Mild steel, screws into the core, no sealant. Mine weren't rusty, but that's just because my boat was pretty much unused and stored indoors. Otherwise they would have looked just like yours.
At first I figured I would remove them and tab the cabinetry in place. I've done fiberglassing/tabbing before, so it was the natural first thought. I didn't want to have to remove the "paper" (white) coating from the furniture, and I wanted to keep the furniture removable, so I was going to do it Albin style, and lay the tabs up against a barrier (packing tape) on the furniture side, then screw the tabs to the furniture (but they would be glassed in the usual way to the sole).
This was going to turn into a slightly bigger mess/project than I wanted at the time, and too, the furniture is totally non-structural, so my mind turned to other ways. I started with the water-tank locker, since I had it apart. I decided to use pre-formed fiberglass angle (McMaster-Carr), slice it into small sections, bond them to the sole (epoxy or methacrylate), and screw them to the furniture. They would cover the old holes (which I overdrilled and filled, to seal the core).
This worked reasonably well, but was a bit fussy (getting the angles smooth and nice, plus dealing with the angles that were not exactly 90º). And it still felt like more than was really needed (not that that usually stops me :wink: ). So I decided to try something even easier, since it would be completely reversible if it didn't work out: I bought some slightly larger stainless steel angles, and bonded them to the sole with epoxy (WEST System 610, which oozed up into the screw holes for a "lock"), then screwed them into the furniture. On most of them, one new screw hole fit into an old one, and the other old one was covered (then there was one new one). I was able to easily custom bend the ones that needed non-90º angles. The furniture is removable if desired.
Now, this is not structural in any way. The angles are only bonded to the gelcoat/glass surface of the sole. So there is the chance I will see some failures. But maybe not. I decided to try it, because if they do "fail," nothing will really happen, and I will be able to cover up any resultant issues (most likely a bit of sole top layer peeling up) with real tabbing or a fiberglass angle without too much trouble.
We'll see how it goes. I will try to put some photos in my Sunbeam thread at some point in time.