Legacy software in general, and in the DoD environment in particular, presents an ever growing maintenance challenge to program managers. The software is cumbersome, written in arcane languages and hosted on aging technology hardware. One of the options that is available to the program manager to alleviate this problem is to reengineer the existing software product and update it to a newer language software hosted on modern equipment. We review existing research, select a reengineering methodology, develop an implementation strategy and then perform a case study examination of this methodology and strategy. For the case study, we take a legacy system, the Navy satellite communications multiplexer, the TD1271B/U Multiplexer, examine its existing documentation, develop a code analysis tool, perform the reengineering on one of its subsystems, and analyze the results. We provide observations, recommendations and conclusions on changes, enhancements and pitfalls to the methodology that will be of assistance in future reengineering efforts of legacy systems.