I did my fastback with six jack stands. Just make sure to spread them out logically and put a few under the rockers it's not that hard to support a hard top car.
I will never try to "patch" a floor again, it's just to dam easy to drill spot welds, punch new holes around the perimeter and where the floor supports go, and rosette weld. I used tech screws to pull everything into place and then worked myself around woth the welder. The bottom looks like a new car now, and is much more rigid than most cars with a patchwork floor.

It's worth the work for the results in the end.
I get a kick out of people that patch a floor and then ask about sub frame connectors?

 

I've never gone the full pan route but have done the individual pans route a few times and I find the extra welding is not a big deal at all since once the welder is set up, doing some extra welds is quick and really no big deal. It does take some extra time cleaning up the welds afterwords if you want a really pretty job. I used to mess with alot of grinding afterwords to clean it up. Now I don't bother too much since once the sealer is on and the carpet is down, you don't see it and i do driver quality not concourse restorations. I could see the benefit of using a full pan on a concourse restoration since it would look cleaner underneath the car.

 

did you do this with the engine, trans, suspension, etc. still on the car?

 

Trans out, I was going to do a swap anyway. The rear end and springs were also out. I would drop the rear end, the cars weigh little on the back half without that lump back there. As you can see by the pics the floor was only a part of the job, but in reality that in itself was not that bad, I just had nothing to connect the new floor to.

To be fair I changed out the floor pan extensions at the same time since they were beat to hell by a floor jack or a dead hobo that got ran over, dunno? I just took a sawzall to the floor and removed it and then was able to stand up in the center and deal with spot welds around the left over edges.

The rockers are the thing, if they are solid you will have no issues on a hard top car. Lets be honest, how much strength did my floor really give my car anyway? I mean it was not correctly attached to the toe boards or the rear torque boxes for the last decade or so and the rust was pretty bad, it wasn't even connected to the wheel houses, they were sketchy, I had to replace the drivers side.


Since my frame extensions were off the car I could slide the new pan in from the underside, then clamp the new extensions in place for mark-up of the floor holes used for the rosette welds on the extensions. Then I put a few welds on the new extensions to hold in place while I clamped the trans x-member in place. Its a puzzle, but if I can figure it out it cant be that bad? ..... Those frame extensions have ten plug welds on each side, I did those last since just a few held them in place. A big spot welder would rock there!

Before (Nasty)




During









After, note the jackstands that did not move all winter.



I did the transition first, but I left the shock mount in place to keep everything square. Once it was in and done I proceeded to the floor. The drain holes are a great place to shove a pipe to pull the pan around while you are screwing it down in about 37 places. I also found a few ratcheting tie down straps through those drains and around the rocker helped keep it snug. I coulda just took the floor back out and stood on the hump to gain another 1/4 of overall width, but it was not that bad.

Transition. (Basically I started at the rear trunk brace and worked my way to the firewall.)


I have always wanted a fastback with a perfect underside, so this is kinda been a goal since I was 19 and had a rusty car with no hope of a proper repair, I sold it and waited till I had the ability and room to do it to the best of my ability. To be honest this took very little welding skill, just a ton of patience and about 9 Harbor freight spot weld cutters.

Here is a photobucket of a rustbucket...

 

Man, looking at that I wish I woulda bought a better car to start with LOL.

 

I wish I could have just bought an already restored mustang... but then I'd have to live like a normal person in my free time

looks like a heck of a job though. I don't have access to a lift. Hell I'm just happy to have a garage to work on the car in.

Do you think that it's necessary to drop the trans/driveline out when doing the replacement? As it stands this looks like a pretty hefty job all on it's own. i'd rather not have to go through all the other stuff as well. I guess the main thing I'd have to worry about is getting the new floor pan in the car, but I think the doors may be wide enough to simply shimmy it in through the door. I may look into removing the windshield and inserting the floor that way as well.

Of course I'm still debating on replacing the whole floorboard... Really the only part that's bad is the front driver and the rear driver side isn't looking very good but isn't really bad... yet. So I know for sure I'll replace those 2 sections, but all of the passenger side is perfect. No rust anywhere.

replacing the whole floorboard at once may be the more "complete" way to tackle this, but the more I think about it, patching just the driver side seems much more cost effective and at least 1/2 the hassle.