There are four Pontiac shock absorbers on all rear-wheel drive vehicles from this manufacturer. There are only two on the front-wheel drive vehicles where Macpherson struts are on the front of these models. The shock absorber is the hydraulic system that was designed to control the bounce of the body when the vehicle encounters an obstruction in the roads surface. Because it is a closed loop hydraulic system with polymer seals, in time they will rupture requiring the owner of the Pontiac to replace them. The life expectancy of the Pontiac shock absorbers is many years under normal circumstances. The more aggressively they are used, however, the shorter their lifespan will be. To determine if the shocks absorbers on your vehicle are performing as expected, the owner can conduct a bounce test on them. This is a test where the dampening power of the shock is put into action so it can be visibly observed. A corner of the Pontiac has to be manually depressed as far as the owner can make it go down. Once released, the number of times the body goes up and down before it stops at a resting position has to be noted. A new shock absorber will rise once then back to a still position. As they age, the number of times the body moves up and down increases. If the body moves up and down two or more times it is recommended that they are replaced. Since all of the shock absorbers on a Pontiac are of the same age, their wear will be similar and should be replaced at the same time. The final outcome will be a smoother ride for the passengers and reduced vibrations for the components on your vehicle.