That crossmember IS structural. Try getting rid of it altogether, your body mounts will shred your floor...
![Wink ;)](https://board.marlincrawler.com/Smileys/marlin/wink.gif)
I took mine completely out and replaced it with a 2x2x3/16" tube welded to the top of the frame a bit farther back. I may have to get rid of that and go higher when I put the rear disco in there.. we'll see.