Thanks John, I would appreciate that. Basically what happened to my 423s is the threads stripped out on the brass plug which seals the screen in on the bowl cover. It had never sealed correctly since I had it professionally rebuilt about three years ago, and possibly had been a problem before then. The threads then finally gave way a couple of weeks ago. As a result, I don't really care about any other missing parts or overall condition of the carb other than the bowl cover being intact, usable, and able to fit on my 423s. Having talked to several more knowledgeable folks than me, the consensus seems to be that the cover from any of those models "should" work. Thanks again,