If you're serious about the boat and/or have actually purchased it, can't you simply measure the locker?
Not sure why you responded since you don't own a 322, but since you asked...
The boat is in Michigan. I am in Indiana. I have inspected the boat (twice now in 4 years...long story). Won't see it again until I take delivery. Did not realize there were so many sizes/shapes of propane tanks ( I am just thinking 20# BBQ grill tank, but pretty sure that won't fit.)
I thought maybe a helpful owner of a 322 would be able to give me the size so I can have a tank ready to take when I deliver the boat from Michigan.
Thanks to the 322 owners who gave me a helpful response.
Greg