I've a 1969 sea nymph with the old screw in drain plug in the floor. I've been using one of the expandable rubber plugs but it always leaks a little and I'd love to find something that would work to screw in like the original. My trial and error research leads me to believe this is a 1" pipe thread, however I can only get the pipe to screw in bottom to top, and that would not seal the hole in the floor . Therefore I assume the original plug had left hand treads, a large head with some sort of seal or o ring under the head and something to grab hold of to turn it tight. Where o where would a fellow find something like that?