It is the Plymouth drive and serpentine belts that provide the required power for the accessories that assist the driver in cooling the passenger compartment, generating electrical power, and steering the car. The drive belts receive this centrifugal motion from the crankshaft. The actual pulley on that engine component is called the harmonic balancer. It is the lowest pulley on the front of the motor in the center of the Plymouth engine. These accessory drive belts are made from a reinforced polymer that is flat on four sides and in a circular pattern overall. They are designed to fit over two or more pulleys so the transfer of centrifugal motion can be harnessed. Drive and serpentine belts are made to last for many years but in time will start to crack, split and fray upon being used. This is just what happens to polymer components on your Plymouth. They are only made to last for a limited time span so damage to the components they come in contact with will not be damaged. The difference in the Plymouth drive and serpentine belts is the number of belts on the front of an engine. The drive belt system makes use of individual belts to drive components. The serpentine belt system uses just one belt to supply the centrifugal power requirements of all the accessories on the front of the engine. There are advantages and disadvantages of both the drive and serpentine belt systems on a Plymouth. The serpentine belts are easier to change, but if one breaks none of the accessories can function. What they both have in common is that the both can crack, split and fray causing the need to have them replaced.