The existing coordinate system for the entire country of Ecuador is the Provisional South American Datum of 1956 (PSAD56) which originated in La Canoa, Venezuela. This coordinate system is considered one of the major datums of the world and is generally associated with the countries of South America that comprise the Andes Mountain Range. The system is referenced to the International Ellipsoid and is rigorously constrained by gravimetric observations. Shortly after the fall of the Iron Curtain, the traditionally classified gravity system of the U.S. Department of Defense was offered to private geodesists on a case-by-case basis. The Guayaquil project was one of those offered access to the WGS84 geoid. The availability of cartographic data in different datums made it necessary to create a new application software. This software needs to look at the input and output of all the components and consolidate all the information into a final depository a block based Geographical Information System (adjusted to the World Geodetic System 1984 using Normal Mercator projection). This paper shows a Molodensky seven parameter transformation shift from a PSAD56 classical geodetic system to WGS84 Word Geodetic System 1984 for precise urban mapping applications. All future work within the city of Guayaquil will be able to use the GPS technology with no systematic bias. Such facility using the PSAD56 system is not possible.