This valve cover requires no drilling.  Mounting of the valve cover, requires installing allen screws into the front and rear holes of the cover, these are used as alignment dowels to set the cover on the head.  After you have the valve cover off, you will have to add the rocker stud brackets.  These are the brackets that come on the late model 4.2 motors, which use two nuts that tighten the valve cover down to the head.  These are the nuts that are on top of the valve cover.

Everything needed to install this cover is included in the kit.