question 1969 dodge dart rear seat belt seat brackets?

[USAJon]

mary's 1969 Dodge dart Custom has these brackets on the front/bottem of the rear seat to clip the seat belts on when not in use. is this stock or an option..never seen b4?
trhnaks.

 

[pntastar69]

These? I had them on my very low optioned 69 Dart, /6, 3 on the tree, radio delete, granny car.

 

[USAJon]

yep! thats it. slant six auto w/radio here..they worth anything?
Marys going to sell car for $975 el rusto