That looks a lot like the shield for the nose of a mid-ship fuel tank.
But mine is plastic.
Can you add something to give us a sense of scale, or just state how big it actually is?
Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.