Overgrown Bumper Syndrome?

[TugOwar]

When I found my 68 GMC sitting in a field and went to look at it, one of the first things I noticed was the rear bumper (pic #1). The way it extended along the bottom edge of the rear quarter all the way to the wheel opening on both sides and then bolted THROUGH the quarter panel. "That looks horrible", I thought. The weld between this extension and where a normal bumper ends was obvious, this had to be some sort of after market mod.

"Why this extension?". I wondered to myself. Perhaps the previous owner had a problem jack knifing trailers into the side of the bed. Not impossible when backing a short trailer. Oh well, it was also one of the first things I tackled when I got it home. A blue wrench and side grinder later at it has a normal step bumper again.

THEN, I see this pic (pic #2) posted by TXFirefighter. His truck he traded to someone else. And I noticed a very simular extension on that rear bumper.

Now whats up with this? Two owners in seperate parts of the country had the same idea? Yeah, possible I suppose. Maybe this some sort of factory option?

Any ideas?