Silverstar - I haven't finished the swap yet. My son is driving on old Chevy Blazer. The last time he came home we completed everything up to dropping the tube. Hopefully we will be able to finish by the end of this month. I'll post everything once we complete the job.
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galwaytt - keep in mind that a used part from a junk yard most likely has been sitting in the vehicle with no use. Just put this picture in your mind. Rubber disc sitting in an open area with exposure to humidity and heat and no rotation. A good example is a tire on a car in a junk yard for a period of time. Pull it off and you will find dry rot, especially here in the southern part of the U.S.A. I agree with you that a part in use that is not abused will last for a long time because the rubber is being flexed. Rubber that is not flexed will corrode. Even new rubber parts have a shelf life that is determined by the storage area, temperature and humidity. Location is the main factor. The 3 - 5 year time spanned as I mentioned above is from research in Atlanta, GA.