Not positive on the steel vs alloy lug nut being different on all models / years. I do know that on most of the SD model years they are in fact different. The ones for alloy have an integral washer whlie the steel don't. Do NOT use the wrong ones. They will not work properly and are dangerous if used on the wrong wheel type.

jake00 - If yours are stock alloy wheels they should be 165lbs according to the book. Check with a ford service center to be safe.