## Existing line
my $im = $graph->plot(\@data);

my $gd = $graph->gd; ## get a drawing handle

## blank out the new Y-axis position
$gd->filledRectangle( 16,0, 48,300, $gd->transparent );

## Copy the Y-axis to the new position
$gd->copy( $gd, 35,0, 0,0, 15,300 );

## Blank out the original
$gd->filledRectangle( 0,0, 16,300, $gd->transparent );