Bulkhead:
The gasket sits in between the locking nut (hand tight only) and the AFT flange. The gasket sits inside the tank against the glass and the AFT flange. If you look at the exploded view diagram the gasket is the shaded portion, the AFT flange right above it (mating surface), and the locking nut is below.
Filter sock:
This will hang onto the sump wall.
The gasket sits in between the locking nut (hand tight only) and the AFT flange. The gasket sits inside the tank against the glass and the AFT flange. If you look at the exploded view diagram the gasket is the shaded portion, the AFT flange right above it (mating surface), and the locking nut is below.
Filter sock:
This will hang onto the sump wall.