Looks like the typical rust areas for an E. IMO, it would be best to remove the entire pan,, drill out your spot welds all the way around the entire thing, carefuly remove your lock and filler tube shield (what else do you call it?
) be carefull you dont drill thru the frame rails,this is where spot weld cutters really come in handy, use a cutting wheel to slice along the tail panel (stay a couple inches in for final cut and fit. Year one has about the best deal on trunkfloor with new fuel tank supports +/- $150.00 plus freight. Also check you extentions if the floors rusted, id be willing to bet the extentions are too,, Hit them with a wire wheel top to bottom, If you also need them replaced autobodyspecialt probably has the best deal on them. take your time,, youll have to work the panels some to get a good fit (It;s hammer and dolly time
)lay the new panels in place to get your final cut along the tail panel,, be careful you dont slice thru the
lower panel where your bumper bolts thru ( what do u call it) If I can replace a trunk pan and extentions anyone can, my mistake was I idnt take pics of it as I went duh,, good luck,,, have fun, happy cutting and welding