Quite possibly on the J/29. A former TPI worker told me that when they were making J/29s they shared J/30 production molds.

Try checking with Alan Veenstra at Chicago Sailing Club with contact info here: http://www.j30.org/html/market/boats.html

He just parted out an old J/30 they had. Maybe he has the sliding hatch. If you speak with him, verify which hull he parted out #119 or #346