You guys are right; that one does require o-rings. I went back in my Amazon orders and I see I ordered two
Dorman 800-153 STEEL FUEL LINE REPAIR KIT. 3/8 IN. x 18 IN. w/16mm fitting. Those have the correct metric o-ring fittings for the filter ends, and I flared the other ends for my carb and fuel pump inlet. I'd forgotten about that.