WHAT IS THE PROPER ORIENTATION OF THE SENDING UNIT?

The sending unit bolt-hole pattern is offset slightly to ensure that the sending unit only fits in the desired orientation. The bolt hole pattern can change with different tank models/manufacturers. Take the screws and gasket off of the new sending unit. Place the gasket on the tank, rotate it until the holes line up, and mark the edge of your gasket. Place the gasket and screws back on the sending unit, matching up the gasket holes with the sender holes. Attach the sending unit to the tank, tightening your screws down in a star pattern. This ensures the proper seal for your sending unit.