...does anyone know where I can get this piece. I cut it out of my car because the lower half was too thin after cleaning the rust off of it. I'd like to get the replacement piece. If it isn't available, then I will have to make it myself...
Dave...

That piece is not part of the longitudinal, but part of the hinge post; it covers over the nose of the longitudinal. They may be someone duplicating the part, but many just fabricate it.

...so it's the hinge post support. The leading edge I left intact, however I removed about 75% of it. It is simple enough to reconstruct. I'm in the middle of welding in the rear chassis stiffening kit right now. It is part of a few odds and ends that have to be completed prior to applying epoxy primer.
Dave