Chevrolet four-wheel drives are identified by the K in the model code: plant serials to 1971, the thirteen-character VIN of 1972–80 and the seventeen-digit VIN of 1981 under the 1GC (truck) and 1GN (Blazer, Tahoe, Suburban) WMIs.
Plant serials to 1971, a thirteen-character VIN 1972–80 with K for four-wheel drive, and the 1981 seventeen-digit VIN under 1GC (trucks) and 1GN (Blazer, Tahoe, Suburban).