How do you get at the back plugs of a Ford F-250 5.4 V8?

if theyre ne thing like the 351 use a step ladder to elevate urself and use just a regular hex to get them off or a socket wrench with a 16 or 21mm plug head on it. I'm pretty sure its 21mm

Amendment - by PayDayBill

Try going in from underneath the truck. If it is a newer model ( like on a 2000 Explorer ) you might be able to unsnap flaps in the wheel wells to gain access from the side.