GOt some Stage 8 locking header bolts for a 4.6L and will also work on a 5.4L. Brand new in the ford mortorsports box. THe cheapest i found them was 39.99 plus shipping. Will sell for $45 shipped. Heres a link to there website.
http://www.stage8.com/AutomotiveStart.htm
http://www.stage8.com/AutomotiveStart.htm