Hi
I am about to take out the drivers seat, I live in Sweden and we have Metric so what size is the nut under the car ? As i need to try to buy a tool to unscew this nut ! Its for a 1966 GT Fastback
Thanks

 

I believe those are 5/16 studs and use a 1/2" nut. A 13mm socket should do the trick. I would use a rachet and extension to get to the bolts as they are recessed. There should be rubber plugs you have to remove to access the nuts, but they may have been removed by a previous owner.

 

Be care full not to drop the nut inside the floor pan

 

Thanks very much for the quick replies.
Seat is out and going to be reholstered

 

Use a six point socket if you have one, it will grip the 1/2" nut a little better.