I GM04 389 NOTE 1 SEE BRAKE MASTER CYLINDER ILLUSTRATION IN GROUP 4 000 FOR DETAILS RPO DEFINITIONS I JM4 BRAKE SYSTEM POWER FRONT DISC REAR DRUM ANTI LOCK CAST IRON I I V I j 1993 GENERAL MOTORS SERVICE PARTS 0PERATIONS PONTIAC 25J 2 93 use 4 000 GROUP