How to remove/install skid plate nuts&bolts?

So I am going to swap the trans and diff fluids and got under there to give the drain and fill plugs a shot of penetrant and let it sit overnight before removing. Some where in another thread about this procedure someone mentioned that the bolts for the front skid plate broke while removing to get at the front diff so I gave them some lube too.

Question: If I remove the bolts to pull the skid plate to get at the front diff how does one access the nuts to replace? These are the two towards the front of the truck. They are located in the cross frame and it seems like it would be one hell of a time getting back on due to there being no space to get fingers in there to line up the nut to bolt. Do they just screw in to a threaded portion of the frame?

This is a 2006 reg cab. Thanks in advance guys!

 

Yeah that's what I kinda expected, thanks whippersnapper02.