The replacement pendant sold by
www.drmarine.com for O'day 192/222 is a narrow, long shackle, might even have been a Wichard, spliced to the shackle with a tight eye on 5/16" double braid polyester line. The shackle seems really long, until you try to put it on the centerboard hole, then you realize that it's just about the right length. It is also narrow so that you don't have problems with a wrong sized shackle binding against the bottom of the centerboard slot when you bring up the board.
So, if you have this config on the boat, you will have to cut the pendant line just above the end of the eye splice, then attach the unspliced end of the new line, so that you can pull the new line up through the pendant tube using the old line as a messenger.
Meanwhile, you'd unshackle the old one, and shackle on the new one from under the boat. It will be about 3 feet under water, maybe 4, because the hole is about 1/3 of the way up the centerboard.
When I did mine, I had the boat on a lift at a friend's, so I only held my breath figuratively. But hold it I did, because I had taped the 2 lines together with masking tape, so I was concerned that the lines didn't separate as I pulled them through. They didn't, the operation was very easy. But if you're doing it in the water, you will need a more physical way to connect the lines than tape, on account of everything being, well, wet.