I also had the originals in my '02 until recently. Did not think they would last through the upcoming winter. That sucks...I still have the originals in the jan.01 2002 and are still going strong, most batteries are good for 4 to 5 years but if you get 7 or more years you are doing well.
I generally have used 5 years for a lifespan. I'm going on 6 years with the original AC Delcos and figure I'm on borrowed time.