71Duster:Retractable front seat belt by the door/floor,or just a seat belt strap like which is used for the back seats?

Hello,I am wondering if my front seat belt retract mechanism was cannabilized out of my 71 Duster Twister,equipped with bench seat,and replaced with a rear seat belt strap,or was this a cost cutting,and clever,measure used by Chysler,like pop out rear windows instead of roll down windows.My 69 Dart has the front retract mechanism. Thanks for any info.