That rear sill definitely seems like its missing some factory seams. I would bet its hiding rust behind some bondo.
That is what I like to refer to as the "paint guy needs this before lunch but I'm not done, **** it boss man says bondo and send it." And then they didn't even sand the edge. Not a good sign.
There is a distinct lack of under carriage pics. @OrangeJoe either you left them out or the seller did. I'd be poking my head in behind the rear wheels at the backside of the tub. Maybe the seller patched it up, but they applied a s*** ton of bondo over the topside.