The first three digits are the country of manufacture.
Per the wikibooks site.
Also mistake on Country codes…GMC light trucks are not listed. The code is 1GT which indicates Ft Wayne, IN. Missing 2G6 on Country Codes.
WMI Marque Country
1G1 Chevrolet United States
2G1 Canada
3G1 Mexico
KL1 South Korea
9BG Brazil
8AG Argentina
8GG Chile
8Z1 Venezuela
