1996 GMC Safari Engine: 4.3L V6; Front; Vacuum Bypass Heater Valve | 6 Port; Position: Front;. 1997 GMC Safari Engine: 4.3L V6; Front; Vacuum Bypass Heater Valve | 6 Port; Position: Front;. 1998 GMC Safari Engine: 4.3L V6; Front; Vacuum Bypass Heater Valve | 6 Port; Position: Front;.