If your PA-28 is as old as our Arrow 2, this start needing replacement. Somehow the over the shoulder seat belt mechanism enclosure got lost. Well this is just another part that we could design up and print.
 
Now you might be wondering... which side is this fore, the left or the right? Well they used the same one for both. The OCD in me still shakes at the thought of it ;P.
 
There is no STC for this part. This is not a legal replacement part for your certified aircraft. So use at your own discretion.