Applications that use the Single-Shoulder pulleys:
P1SC, P1SC-1, P1SC-2, D1,D1SC, F1, F1-A, F1-C,F1-R Superchargers
2011-2014 Mustang GT Shared Drive 6 Rib SS
1999-2001 Mustang Cobra 6 Rib SS
2003-2004 Mustang Mach 1 6 Rib SS
2001-2001 Mustang Bullett 6 Rib SS
The reason for the single shoulder is because of the alternators size. A standard pulley would rub the alternator, so thus the shoulder has been removed.
Mach 1's, Cobras, and Bulletts all share this common alternator.
If you do not see your application listed, please check the other pulley areas of this site. Or drop us a call at 816-340-6755 for questions.