Ok, so you confused us all again. [&:] i covered this subject awhile back. set your gps map datum to NAD 27 and use UTM and life will be very simple for you. UTM grids are allready on your topo maps, just a matter of drawing lines north and south and east and west. when your gps brings up the UTM position, you use the last five numbers only. first two of the top and bottem numbers will get you in the grid, last three numbers of top and bottem will take you exactly to where that position is within the grid. just as simple as that.