The Slant is leaking from the Carter BBD

I have the 66 dart with 225 slanted 6. Swapped over to Super Six about 2 years ago.
Over time it seems to have developed a gas leak out of the carter bbd, which I have rebuilt twice in 2 years hoping to fix the leak.
It seems to be leaking gas out of the carb, down the front and then onto the intake manifold. At first I thought it was the fuel line, but have ruled that out with Gasolina sealent. The little vacuum plug is always coated with wet gas. Any ideas on what is happening? I keep tightening the screws that hold the carb together, they seem to loosen every few months.
What is this thing just below the fuel inlet? is that some sort of bushing? certainly seems to be wet with gas. helppp//.....

Carter Carb Leak - 1.jpg Carter Carb Leak - 2.jpg Carter Carb Leak - 3.jpg Carter Carb Leak - 4.jpg