This page shows how to replace the O-rings on the HPOP on a 7.3 litre powerstroke diesel
This is a job that can easily be done in a couple of hours, you'll need Viton #6 O-ring or the 2C3Z-9G804-AB kit from Ford.
It can be done with the hoses left on apparently, but IMO it's a whole lot easier to take them off.
I made a tool from an old bicycle wrench in about 30 seconds with
a grinder (see pics).
If you have big hands you'll find it a little tight, but it's doable.
Better yet try and talk someone with smaller hands (like your significant other perhaps)
to do it for you while you supervise and enjoy a cold beverage.
(if you can pull this one off let me know how!)
Click on any image to view larger image, or right click on image and
and choose "save
link target as"
or "save target as"
to save image to your hard drive.
(note: I use firefox to build and
display these pages, if you are using IE you may have to enable java
script to view these thumbnails.)