Where can you find track vehicles?

The document TC 21-306, which stands for Training Circular 21-306, specifically covers track vehicles and provides detailed information on their operation, maintenance, and training procedures. It serves as a comprehensive guide for personnel involved in the management and operation of track vehicles, making it the most relevant source among the choices provided.

To understand the context of the other documents: AR 611-5 pertains to the U.S. Army’s personnel classification system, FM 55-509 deals with movement control operations, and EM 700-12 focuses on emergency management and operations. While these documents are important for their respective areas, they do not provide specific information on track vehicles like TC 21-306 does.