Well simple answer. You really can't and if you know it's those 4, get them replaced obviously. To get into depth you would have to know your car top to bottom. And common problems on other forms and TSB's. After having that knowledge, then follow it and don't buy cheap stuff or rebuilds if you don't want to risk anything. After that, then just check the car every oil change to see if anything is up. Most problems, you or your mechanic should be able to spot right away, through scanning the car or just a fully complete inspection. Preventive maintenance I believe is the term you are looking for. Can't really fix something that hasn't broken yet... Replacing parts just cause you feel like everything is about to break anytime it is a waste of money. If this vehicle makes you unsafe, better get another car.