Curt -
Maybe someone who has a shallow-bowl Durex filter with the thumb bolt through the bowl can give a better answer than I can.
Seems like there should be a gasket where the bolt goes through the glass bowl. I don't have that model Durex filter, so I don't know for sure. I looked at the photos that I have gathered and didn't see a gasket either.
My vote is to cut a cork gasket to fit under the lip of the bolt. Can't hurt, might help. Just be ready to shut off the engine the first time you start it with the filter in place. It's amazing how much gas the fuel pump pushes past a bad gasket ... don't ask me how I know this!
By the way,
here is a good article on the benefit of replacing cork fuel gaskets as they age. (Lower right corner of the page.)
Post some pics of your new filter when you finish the installation. It's a neat filter.
