turn signal housing

Can anyone tell what kind of fasteners are used to mount the turn signal housing to the front bumper on a '69 runner. Almost done here but I know what I found holding them on is wrong....
Thanks all for help with this project
Bruce

It's called a nut cage...not sure if it's 5/16-18 or 1/4-20. RT Specialties has them. See link below. http://www.rtspecialties.net/proddetail.asp?prod=1003798