During the beginning of the Advance Design years (1947-1949) new Chevrolet Suburbans were sold in one color combination; Channel Green (light) on the lower body and Fathom green (dark) on the upper.
Unless the customer paid extra for a specific paint such as for school bus use or a commercial paint color for a company, the two tone green was the color your received.
Beginning in 1950 this changed. Chevrolet began also offering 12 colors as on pickups and large trucks.
The following is from a 1950 Chevrolet announcement pamphlet showing changes in trucks that year