Corded models:

In the past, the date code was etched into the body of the grinder, and the date serial numbers were on the rating label. Due to input from users, we have moved them to a more protected area of the tool.
Beginning in 2014, both are etched into the gear housing, under the guard as you see in this photo:

Cordless models:

The date code on the corded models is engraved in the battery compartment where you slide the battery into the tool.