Need a nut size

[SmallTownStang]

Does anyone know what size nut the big black one in the picture is? I went to put in a rear seat delete and relized that there was only one holding the bracket down.

View attachment 364867

View attachment 364869

Thanks,
Preston

 

[03redgtstang]

my big black nuts are extra large, not sure what yours are............

 

[2000fordstanggt]

my big black nuts are extra large, not sure what yours are............

 

[Turbo92PGT]

if I had to guess I would say 13mm.

Most of the crap on this car are 8mm, 11mm, 13mm, 15mm,