Bolting up front bumper brackets

Ive searched vendor websites and forums but couldnt find what I need to know. When bolting up custom front bumper brackets do the bolts go thru both frame rails on each side or do the bolts bolt up in between the frame rail tubes? So you would either need (ex.1 3/4" bolts or 4 1/2" bolts). It seams like if you went thru both frame rail tubes and tighted the bolts up tight that it may squash the frame rails. (unibody)

The frame rails have re-inforcing tubes welded inside them that are larger then the bolt holes. If you buy the C-Rok steering box re-inforcing plates, they come with tubes that you slip inside the tubes that are already there, then you install the new 5" long bolts. If you take out a bolt and slip a strewdriver into a hole and wiggle it about, you will finde the re-inforcing tubes.