I have been stressing for decades now that you should keep all parts that are replaced on your vehicle for future restoration of the part, in the event that such a replacement part is no longer available in the future, unless the part is destroyed in removal. An example of this would be an exhaust system, etc.. An example of a part that you would want to keep is the master cylinder. They all look the same for a given year, make, and model, however, this isn't always the case. Internally, they are all different to accommodate different type of braking characteristics of the vehicle. Many parts that people think are the same on a Commercial Chassis look the same as the same part on a De Ville, but upon close examination, there is a significant difference. This is where the original factory parts book comes into play. It will indicate the difference by part number and price. The parts re-builders have a one size fits all mentality, and will list the same part number for many applications and years of vehicles. Problem is that the re-manufactured part will fit, but it will not perform like the original. Case in point is the Commercial Chassis brake booster looks the same as the car unit, but in actuality, it is slightly larger, both internally and externally. You wouldn't notice this difference by looking at them. The same goes for the Commercial Chassis wheel / rim. They look the same, but the Commercial Chassis rim is much heavier steel, and has riveted webs attaching the center section to the outer rim. The standard car rim is lighter in weight and is welded. Both will interchange, but the lighter standard car one might fail, causing you to loose control of your car.