Back seat belt

turns out my 1966 dart 270 4 door is missing the long seat belt in the back seat. I dont need the short side, I have those. But I am missing one of the long belts that the other one clicks in to. Black if possible. anyone got one laying around? Would like to be able to drive my kids around, but currently only one of them can come with me,. I can see the bolt hole that the seat belt will attach to. I am missing the bolt as well.