Dose anyone know the size of the banjo bolt (diameter, thread and pitch) under the oil filter that goes to the oil cooler?

I want to make an adaptor like the one below for a oil temp gauge.

http://www2.ocn.ne.jp/%7Eknight78/PRODUCTS_SE3P/OOAT1.jpg

I think it's 18MM

thanks dan the other thread (http://www.rx8club.com/showthread.php?p=1066857&posted=1#post1066857) has the other info I found.