Do these sandwich between the bumper mounting bolts, or do they use the tow hook bolts?

 

According to the directions (not word for word), you remove the (2) Driver side bumper hex mount bolts. Then place the mounting bracket over the tow hook and line up the bolt holes. Install the (2) removed factory hex bolts back were you removed them from.
The driver/passenger side mounting brackets go around the tow hooks. You dont have to mess with them at all. I will post pics in the AM if it isn't raining.

Note when loosing the factory hex bolts do not remove one all the way. Break torque on both bolts. There is a plate with the nuts welded on it and it will just spin if you remove one of the bolts with out breaking and loosen both bolts.
Also only do either driver or passenger side 1st. If you loosen both sides the alignment of your bumper will be off.

 

Just found this old thread and decided to add the installation instructions for 2011-2014 Ford F250-F550 in case you are looking for a similar bull bar: http://www.carid.com/images/steelcra...structions.pdf

We are the authorized dealer of Steelcraft, so you can find a good bull bar, grille guard or a set of side steps here: Steelcraft | Grille Guards, Bull Bars, Running Boards, Side Steps - CARiD.com