This has not been done, and the sale of y2k testing software so far has been minimal. The U.S. train transportation system is not compliant. Very few power generation companies have announced mission-critical compliance. No large telephone company has announced full compliance. The chemical industry is way behind.
Chemicals are basic to manufacturing, and also to the treatment of drinking water.
Diesel and gasoline are chemicals. No oil exporting country is compliant. The U.S. imports over half of its oil. General Motors has 2 billion lines of code and 100,000 suppliers. If a component is missing on an assembly line, the line must be shut down.