Okay, just so I'm clear, I'll use the pic below...same bulkheads I got from savko:
the gasket (obviously the black ring towards the bottom) gets the silicone on the flat side? and the flat side goes against the inside of the tank right? what exactly is the flange on a bulkhead? is it the top piece in the pic? the one that screws onto the back of the bulkhead outside of the tank?