Seatbelt mount question

Hello! Mopar owner from Sweden here.

I have a Dodge dart GT 1969 that i´m figuring out how to put retractable 3 point seatbelts in the front. I have been looking around the forum and most seem to have a mounting point in the roof under the liner. I havent looked there yet but i got two tapped holes under the quarter windows. If there not mounting holes for seatbelt then what are they and are they factory?

Thanks for any help:)