Love my Weber’s. Got two 2 22 inch grills and a Smokey Joe for camping / tailgating. I can’t tell you how old my first one is but I’ve replaced the grates several times.
I have 2 - 22.5 Kettles, too. Here's my "family," as of now. I sold my Weber "Bullet" smoker.
One 22.5 Master Touch (Redhead) - 1995
One 22.5 One Touch Gold - 2015
One Smokey Joe Platinum (Jumbo Joe) - 1991
One Genesis Gasser - 2001
The Black OTG and the Genesis are outside 24/7/365. The other two are in the garage, until I need them. I also have a Cajun Bandit rotisserie kit for either of the 22.5 Kettles.
BTW, there are date codes on all Weber grills, and date code guides online, so it is easy to find when they were made.