Different email templates per order status. Is it possible?

Sorry if this has already been covered. I did do a search but found nothing relevant.

I'm aware that zen cart uses the email_template_order_status.php file from the /email directory for status update emails in html but i would like to use a second template when the order status is changed from 3 to 4.

How does zen cart call the template in the first place? I globally searched the code for email_template_order_status and found nothing. I was expecting to find a require or include type command or some other code section that told it what template to use.

Adding in a separate template would be extremely easy if i can find where zen cart calls the correct template from, but it's got me beat so far.

/admin/orders.php, line 154:

            zen_mail($check_status->fields['customers_name'], $check_status->fields['customers_email_address'], EMAIL_TEXT_SUBJECT . ' #' . $oID, 
                        $message, STORE_NAME, EMAIL_FROM, $html_msg, [B]'order_status'[/B]);

Thanks a lot DrByte. Just what i needed :)
All done and tested.