Help! .. Where does this part go??

[chillware]

Ok, so I feel kinda dumb about this..

I am getting to the point on my truck where I am almost ready to start piecing things back together, and was going through my pile of parts, and came across one part that I don't recognize or know where it goes back on the truck! lol! ... I tried looking at my exploded diagrams and don't see it on those either. Here's some pics, hopefully someone knows what it is .. at first i thought it was one of the cross members I removed/upgraded but its wider that the frame is. :S I'm positive it came off the truck when i took it all apart.

Any ideas?