For those with the Ford 7.3 power stroke diesels that have a fuel leak dripping down off the engine---the o-ring seal kit is Ford #F81Z-9C065-AA or International Harvester #1831204C91

$39.58 list at Ford discounts to whatever rate you get. You'll need a 1/4 drive ratchet (thumb wheel would be handy) and a 20 and 25 torx

If yours isn't leaking your not burning enough low sulfur fuel yet and its only a short time before it does--

I wouldn't recommend buying the super low priced o-rings you can find on the net unless you want to do it over in a couple months