I installed a brand-new alternator in my 1997 Saturn four years ago. How long should it last?
Every car I’ve owned has been 10+ years old and most of them had their original alternator. The two exceptions were one that had a new alternator at age 8 (the shop marked the date of repair on it) and the other I replaced myself at age 16. In other words, they last *quite* while unless you do something stupid like try running a 2000W amplifier or a refrigerator off of them.