Here is the size from the website:
(7/8" x 14 pitch threads).
The website for information is:
http://www.davisnet.com/marine/produ...asp?pnum=00425
The site for ordering that I got from macojoe is:
http://www.boatersworld.com/product/358500676.htm
While you are at the Davis website,
check out some of the other stuff there,
I found it pretty interesting.