Where is Kohler toilet color code?

The toilet tank model number is inside the tank, either molded in the porcelain or printed in blue or black ink. The model number is composed of 4 digits and, in some cases, includes a K prefix. If you have a two-piece toilet, the bowl model number is molded into the porcelain on the underside of the bowl's rim. The tank lid number is printed on the understand of the lid, whether it is for a one or two piece toilet.