[geckoday]

In skin1/main/history_order.tpl find this line:

<INPUT type="text" name="tracking" value="{$order.tracking}"{if $usertype eq 'C'} readonly{/if}>

and change it to something like this:

<INPUT type="text" name="tracking" value="{if $order.tracking eq '' and $usertype ne 'C'}12345678{else}{$order.tracking}{/if}"{if $usertype eq 'C'} readonly{/if}>