I think Azcowboy has the right Idea....With my GIII+ set to NAD83 I can set my DDD MM.MMM to any other co ord setup.....and when I Upload co ord in DDD MM.MMM and Im set to DDD SSS MMM I end up with a very different set of co ords that I dont think is the mathmatical equivelent. Id make sure you are set to DDD MM.MMM