These parts fail by cracking at the weld or by losing their rubber isolation. A cracked bracket transmits vibration into the component it carries, which is why an alternator or a compressor fails repeatedly and no fault is found in the component itself.
Listings state the side and the position, and whether the rubber isolator is included. A bracket supplied bare means reusing the old isolator, which has usually lost its elasticity.
Heat shields are listed here too. A missing or rattling heat shield is not cosmetic: it protects wiring, hoses and the floor pan from exhaust temperatures.
