How many spark plugs does a diesel truck have

Diesel trucks do not have any spark plugs. A diesel truck has an internal combustion engine, as does a  petrol car. The method of igniting the fuel is different. 
For the purposes of this discussion, an internal combustion engine is an engine where the fuel is ignited and burned inside the cylinders of the engine. This is where the power is produced. 
The diesel engine works in the following way:
1. Air is let into the cylinder and the piston compresses the air. 2. Once the air is compressed, fuel is sprayed into the cylinder. The amount of fuel sprayed onto the cylinder varies. 3. The compressed air is so hot that the fuel ignites and explodes without a spark plug. 3. The controlled explosion pushes the piston back out of the cylinder.4. Enough power is produced to drive the vehicle forward.