5/16 Just saw your post so I am going to call asap. I am going down to Petaluma today???? I will call you on the way and try to send in mail. Just pay me postage back??? Ray cell is 707 467 0815
I should checked the site more often. I ended up buying 105mm (4 1/8") hole saw it from Amazon.
Anyways, I installed the snorkel and here are some pictures.