1966 GMC PB15 Series Engine: 4.8L L6; with 4 Bypass; Position: Carburetor To Governor;. 1966 GMC PB15 Series Engine: 4.1L L6; Position: Governor To Intake Manifold;. 1966 GMC PB15 Series Engine: 4.8L L6; with 4 Bypass; Position: Governor To Intake Manifold;.
