There are two types of glow plugs used on General Motors Corp. diesels: two subtypes, which include the 'fast glow type' and the 'slow glow type'. The fast glow type incorporates pulses of current on to 6-volt glow plugs, whereas the slow glow type requires a steady current and is applied to glow plugs of 12 volts. It is easier to identify the 6-volt fast glow plugs by the fact that they are fitted with a 5/16 in. While the fast glow cartridge employs an 8mm wide electrical connector, the slow glow or 12-volt cartridge uses a 1/4 in. (6mm) wide. The two systems must not be interchanged because they are different from each other in many ways. As for installation, glow plugs possess peculiarities-threads must be lubricated. First, take out the engine support strut, to fasten the intermediate steering shaft pull it up and take out the steering gear stub shaft clamp bolt to detach the intermediate shaft from the stub shaft. This is required every time that the body is shifted in relation to the cradle and necessary to reduce the possibility of damage to the steering gear whereby loss of control of steering may be encountered and accidents likely to happen. Subsequently, put a floor jack beneath the front crossmember of the cradle and rupture it to such an extent that the car starts rising. Both front body mount bolts need to be FI removed along with the respective lower cushions and retainers, it will be noted when removing any one of them the connectors of the adjacent ones have to be loosened so that the cradle can come off from the body. One must be very careful not to crack the plastic fan shroud or harm various other frame fittings such as steering hoses and brake pipes at this stage. Tighten the body mount bolts with retainers this at least three thread turn into the cage nuts to maintain cradle movement and then lower the floor jack until the crossmember ensnare the body mount bolt retainers while ensuring that there are no interfences from hoses, lines, pipes and cables with the cradle. One should never put hands between the crossmember and the body mount when the jack is coming down, and the cradle should be secured to prevent harm to the body and underhood parts.