From the little research I have done it appears 71 Grabbers had a plain spoiler and the 72 Grabbers had a pinstripe on the spoiler ...
Actually...the stripe was just below the spoiler on the trunk lid, and on the spoiler rear quarter extensions.
I lucked out. My bumper chrome is finished and only took a week! Apparantly one of they guys at the chrome shop thought my bumper was a Camaro bumper which was next in line. Chrome plating was done before they figured it out. So I got lucky and cut to the front of the line. Hopefully the chrome guy is a Chevy Camaro fan and maybe did an extra nice job on it!