Under the Kennedy Administration, Secretary McNamara instituted powerful centralization tools in acquisition such as the Total Package Procurement concept (TPP). This system shifted many major program management functions to the Pentagon. Stressing computer modeling, concurrency, and paper competitions among the contractors, TPP sharply curtailed the flexibility of Systems Command program managers. Cost overruns and serious technical difficulties in such TPP programs as the Lockheed C-5 Galaxy and General Dynamics F-111 Aardvark lead to drastic changes in DoD acquisition practices. In 1970, Deputy Secretary of Defense David Packard revised many McNamara policies. He decentralized the acquisition system and reemphasized prototyping in weapons development.