leak at sending unit

I recently installed a new gas tank and sending unit on my 71 Duster. While under the car trying to figure why the gas gauge was intermittant, I noticed that I smelled gas and the area around the sending unit gasket was damp. Any guess as to what I should do to get a tighter fit? Should I look for a thicker gasket? Bend down the metal tabs to get a tighter fit with the gasket I have?