Power Brake System Lt Duty 1784 KG to 1815 KG 2 5R 2 5 5 2 8X JA8 Power Brake System Med Duty 4 3T JA2 Power Brake System Hvy Duty 1983 CHEVROLET ... Power Brake System Lt Duty 1784 KG to 1815 KG 2 5R 2 5 5 2 8X JA8 Power Brake System Med Duty 4 3T JA2 Power Brake System Hvy Duty 1991 GENERAL MOTORS SERVICE