I've gotten to a "if you give a mouse a cookie" point in time and I'm not sure where to go. When I first bought the car, no top, rusted floor pans under the seats. We cut out what was rusty and put sheet metal in its place with self-tapping screws, to hold things in place until I can dig deeper. So now, do I only cut out the rusty bottoms and do new metal, or do I order floor pans and replace the whole thing? My son has experience welding, but I don't. And we've never done this level of work before.

This is not a show car, just a fun driver. Repairs will be covered by insulation and carpet, but I don't want the car rusting out from under me.

 

I would just weld in new plain sheet metal. For a daily driver nobody will care that it doesn't look original.

 

Additionally, the crappy fit we seem to always get from aftermarket parts for these cars, replacing the entire floor pan will probably be a nightmare. I have never had to do this on a 3rd Gen, so I may be way off the mark here, but I have 'enjoyed' trying to get other aftermarket stuff to fit on these cars way too many times. Sheet steel, body hammers/dollies and planishing bag and you should be golden, especially for a driver.

 

If you can't weld in the sheet metal I would recommend you use 3M panel Adhesive to go along with those sheet metal screws.

 

The aftermarket floorpans do fit pretty well. I used one to section the passenger front footwell/converter hump into mine.

In the OP's situation, new floorpans are the "right" way to go, but they are a good amount of work to do. Not really hard, just a lot of work. I'd look at the rest of the car to see if there is also rot in the common locations (wheelhouses, rocker corners, cowl/firewall, etc.) and then decide whether or not to go forward with repairs.

 

Good to know. Luckily, none of our cars are from the rust belt, so don't need that. Our SVO did have significant rear quarter damage (seems even 4-cyl Mustangs can get away from their drivers), and while I got two take-off rear quarters, the body guy only used a portion of one and then just aftermarket patch panels for the other side. He, too, commented that the patch panels matched pretty well, so went that route for the repairs.

I'm once bit, twice shy about aftermarket parts for GM F-body cars, though.

 

I’m in agreement with you regarding poor fitment of aftermarket body panels for the thirdgens. Aftermarket fenders, hoods and bumpers are pretty bad. But, those need to be just right, otherwise it’s very noticeable. Underbody parts, like floor pans are a lot more forgiving in that regard.