MaxPF
1/2 ton status
I crawled up under my ride, and what did I find:
That's one of the rear nut plates for the drivers seat bracket
The other was hidden under the old cat con heat shield. When I got the heat shield out of the way it wasn't pretty:
Here's some top side views:
Not good
I got the carpet and padding out of the way and welded up the cracks as best I could from underneath. Then I put a piece of 1/4" thick 4" wide plate on the top side as reinforcement. It's solid as a rock now, although I kinda miss the suspension seat feel 
That's one of the rear nut plates for the drivers seat bracket
The other was hidden under the old cat con heat shield. When I got the heat shield out of the way it wasn't pretty:Here's some top side views:
Not good
I got the carpet and padding out of the way and welded up the cracks as best I could from underneath. Then I put a piece of 1/4" thick 4" wide plate on the top side as reinforcement. It's solid as a rock now, although I kinda miss the suspension seat feel 
I have different seats and through bolts with plate on interior side , and washers on underside . 