The 23 changed a lot
There were at least three different versions of the Oday 23. Check out the Unofficial Oday Website (listed in the links section of this site). It has a very interesting and detailed history of the model. I know that when I was looking to buy one, I came across an older ('73 I think) pop-top model. The salon table was on a post, and the centerboard was raised with a crank that was mounted on that post. Now that you mention it, the interior did look more like a later model 22 than the later 23. I think the lines of the hull on all models of the 23 were identical. I do recall that the older 23 I saw had an cutout in the transom to accomodate an outboard, as opposed to an exterior engine mount on the later models. One thing for sure, I saw about 6 Oday 23's before I found the one I bought, and only two of them were identical. As to wether you can buy a stern rail, according to the old brochures, it was an option on the 23, but apparently not a popular one. I never saw one built later than '79 that had one. Since Oday is long out of business, your best bet is to check with Rudy at D and R Marine (website also listed in links section) to see if he carries them. If not, you can see if a Catalina or other current manufacturer's existing replacement parts fit. Otherwise, you are looking at a custom marine fabrication job. Rudy also has the "owner's manual", which is really just a two-sided sheet of 11x17 paper.