The hood pins would have been dealer installed or purchased over-the-counter. Should be only factory installed on GT-37's.
The asterisk (*) indicated a standard (No charge, I believe) option for that particular grouping or model.
451 AK1 Custom Seat Belts and Front Shoulder belts
452 AK2 Custom Seat Belts with Front and Rear Shoulder Belts.
454 A39 Custom Seat Belts
Shoulder belts were black only. 1971 Fisher Body Manual has a basic picture on page 14-87.
http://www.forums.maxperformanceinc....d.php?t=669429 (wrong thread, that's for '72s)
http://www.buickperformance.com/RearShoulderBelts.htm