Chances are pretty good that it's stainless...
If it's original, or the previous owner knew what he was doing, it's most probably stainless steel. My previous owner (or his previous owner) might have been a few sandwiches short of a picnic (IYKWIM). I found a real mess when I replaced the cable. The winch was wrong, it was an old trailer winch and the cable was 1/4" non-stainless, so it came as no surprise that it broke. It broke during my first sail, in about the first 10 minutes. Fortunately there was a heavy concrete boat ramp to catch the keel

.After replacing the winch/cable/bolt the winch board broke ,or I should say, disintegrated. I don't know the winch location on the 22 but mine is in the cockpit by the companionway, mounted to a 6"X4" pressure-treated board.Also, I guess there's also a tube that the keel cable travels through, check this for leakage also.Good luck, and check your keel pivot bolt also...I haven't changed mine yet, but I need to do it this winter..-=gp=-.