Fuel Filler Neck Assembly: New, Spectra Premium Industries FN664 Filler Neck Assembly, which includes screws and plates. Drawing P/Ns 2, 7, 9, 12, 24, 30. eBay $75.
Sensor and Self locking Nuts: New, drawing P/N 16 and legend 3, purchased at local Subaru Dealership, Subaru Sensor P/N 42084AE100. Ask them for the nuts. Cost $60.
2 ft. of 5/8in. hose, 1.5 ft. of 1/4in. hose, and clamps: New, from Advance Auto, $10
See attached Image,
Here's the link to the image/parts.
You can also get the part off of Amazon.
Amazon.com: Spectra Premium FN664 Fuel Tank Filler Neck: Automotive