How come your newer Neon has a Plymouth brake booster but your old Duster just has a master cylinder bolted right to the firewall? Good question! Almost every Plymouth manufactured since the mid-1970s has disc brakes at least on the front, and will have a Plymouth brake booster to go with them. Your Duster probably has drum brakes on all four wheels and doesn't require a Plymouth brake booster in order to bring down to a stop. Drum brakes have a sort of 'natural assist' that comes along with the design. And while disc brakes require the addition of a Plymouth brake booster to effectively stop your car, they do so with far more efficiency than any drum system is capable of. The Plymouth brake booster is the main component in what's referred to as power brakes. The power comes from your engine in the form of vacuum drawn from the intake manifold. Vacuum acts on a series of seals and diaphragms inside the Plymouth brake booster to boost the pressure placed on the master cylinder, helping you stop more quickly. Nowadays, with the advent of ABS and traction control, the brake fluid has to do even more than ever before. Your Plymouth brake booster helps the fluid get where it needs to go to keep you and your vehicle safe. But everything relies on vacuum being held by your Plymouth brake booster: If a vacuum leak occurs, either inside the Plymouth brake booster or in one of the lines that lead to it, you have no assist. And if you want a jolt of adrenalin, try stopping your Caravelle with no Plymouth brake booster helping you out. If such a situation should arise, get your vehicle stopped safely and then order a new Plymouth brake booster from us. You'll get premium quality at a discount price, and you'll get your new Plymouth brake booster shipped out the day you order.