Looks like whoever replaced the floor in the 69 bird I got decided that the rear most body mounts were optional as the holes and nuts in the replacement floor did not exist.

I need to correct this and need some guidance. Do I need to drill holes in the floorboard? What's the best way to get this fixed?

Is there no cage nut built into the floor?

The replacement floor I have has the holes and cage nuts welded in as purchased. The cage nut floats in the box cage. I don't believe the replacement floor sections that you buy individually have this welded to them unless you buy the complete floor. The cage nut gets covered by the seat pans after it's all put together.

I don't know how you are going to add it without major repair. The seat pans do not come out without a fight. Welded in like an armored car...

I happen to have my old floor sections which have the cage nuts, that could possibly be cut out and patched into your floor but not till I am finished with my floor. I need them for any reference points while I put in the new floor. Still would be a big issue to put these in and properly locate.

it's unbelievable to me that someone would not put the nuts back in if they were doing floor work and took them out....

yeah, pretty wild. I havent stripped the seats and carpet out yet. But I'm pretty sure that he didnt even place the seat pans back in either. Or the seatbelt nuts.

The first floors I worked with required me to remove the old seat supports and weld them to the new pans. I can't count how many welds were drilled out before using air tools to pry both seat supports from the original floor. It sounds like this may be your only option.

My new full floor had everything attached and made the installation process so much easier.

I am never surprised with the lack of effort put in when people who should not be working on cars do work on them. My current project had 3 quarter panels welded on each side. Instead of replacing the original they continued to weld one on top of the other.

Good luck with your project

Garlanka, I had the same issue with Quarter extensions. Didn't even plug weld. picked the welds apart with a screw driver. To think I was driving this car and had my children in it scares me.

I continue to be amazed at how many structurally incorrect welding jobs I have come across. My current project had been painted with a rebuilt engine, just need interior and looked to be ready to go. Mind you I ran a magnet down the car before purchasing it back in 2007, and the magnet stuck. I still decided to to sand blast to make sure everything looked sound. Glad I did. I found the quarter panel issue I mentioned above, along with pop rivets instead of welds along almost every body panel. The best was the freshly built engine with new 30 over pistons. I pulled it out only to see that they had used a compound to cover a crack in the side of the block. Good think I picked the convertible up for the price of the N.O.S. parts that came with it.

Not much surprises me after this project.

Glad to hear that you found the amateur work before something bad happened.

We had a phrase for this kind of stuff back in HS Auto Shop - Micky Mouse. There was also the old autos shop safety movies staring Primitive Pete.

I think it may be good idea to force sellers of welders, and those companies that sell reproduction parts to make prospective buyers watch Primitive Pete videos before they can make a purchase.

It's too bad this is common place.

Unfortunately, it has forced us as the consumer to start questioning the seller more about what was done. At least that is my take on things after being burned on my project. Honestly, I prefer to purchase a car that has not been messed with, even if it is a basket case.

I am going to need to replace the seat frames. Is there an easy way to line these up in the proper place. Markings in the floor? Want to make sure the cage nut for the sub frame bolt is lined up properly.

I used a permanent marker to trace completely around the frames. Everything came out ok for me. You can also take measurements for backup.

There is a bracket that welds to the floor pan from the sill to the center tunnel. This bracket locates the front of the seat pan.

You may want to see if that is sold separately.

The floor that is in there was a replacement and doesnt have any of that stuff. Wondering if there are marker that I can go by when I weld in the new cage nut bracket and seat frames. I don't have a go by.

I can give you measurements off of mine. I think if some others on the site do the same we can compare notes to see if there is much variation to the actual location. I know they would have to be close due to the bolt hole in the frame being drilled in the same location.

Here we go again... You just keep walking into those!

Apparently since the site has been back up and running my comments have gone down the drain.

I have a complete floor replacement in my basement that I could measure some points for you if you wish.

Even a good reference pic would be awesome. I need to pull my carpet and make sure I know what I'm dealing with.

I will stop by where my car is stored and take some shots, still stripped to the bare metal.

Have a look at these files...

Frame mounting for 68 Firebird

Sub frame bushing install

I'll take a picture of the new floor Saturday for you. I'm out till then.

Here is the passenger side seat section. Sorry for the poor quality picture but there is a bracket that runs from side to tunnel which is welded to the floor. On top of this is another small bracket welded and then the cage nut welded to that.

Don't quote me, but I saw what looked like the brackets above selling individually on Ebay. I didn't see the cage nut and the picture was not clear and or zoomable, but it looked like that bracket if that helps.

Thanks a ton for the pics. I took my passenger seat out and as I assumed there is no trace of any of the braces or cage nut bracket.

I'm to the point of looking for a parts car with all the pieces like this that the po has messed up.

As I mentioned, you are welcome to use my old floor which has the usable cage nuts (I could possibly cut them out at a later date), and like I mentioned, I saw the brace on ebay for sale so you might want to look for this. I didn't see the cage nuts welded to it, but that may be a good start.

It will be trouble getting the seat support out without damaging the rest of the floor. I think Brink's did the welding back then, LOL, but again, I have a vert with braces underneath that complicated the removal of these.

A brand new floor will set you back $350, thats got to be cheaper than a parts car, or maybe not? Then you can use what you want, and pitch the rest.