Originally Posted by 
34_40
				 
			I was taught that "If it's ugly, it is weak."
Don't just cover it up with sheet metal, take a little extra time and at least address that open ended section. It shouldn't be too hard or take to long to cut that out and make a piece to tie it all back together. 
The abrupt and open end just leaves the associated stress to be handled by the surrounding pieces that are connected to "something".  If you don't want to fix this, then don't bother boxing the frame , the stresses further back are relatively less that what this area has to handle.
I really don't want to sound harsh, of course it is your truck and your budget / your build....:)        We may have to share the same piece of road someday, I'd like it to be a safe one.:3dSMILE: