Ok I thought you only needed some small pointers...
Here is a code I just wrote for you to use:
find in admin/invoice.php at line 156
for ($i = 0, $n = sizeof($order->products); $i < $n; $i++) {
replace with
for ($i = 0, $n = sizeof($order->products); $i < $n; $i++) {
//manufacture hack start
$manufacture_id_sql = "select m.manufacturers_name, m.manufacturers_id
from " . TABLE_PRODUCTS . " p, " .
TABLE_MANUFACTURERS . " m
where p.products_id = '" . (int)$order->products[$i][id] . "'
and p.manufacturers_id = m.manufacturers_id";
$order->products[$i]['manufacture_id']=$manufacture_id_sql->fields['manufacturers_id'];
$order->products[$i]['manufacture_name']=$manufacture_id_sql->fields['manufacturers_name'];
//manufacture hack end
Then print anywhere in the loop the manufacture's name or id by using
<?php echo $order->products[$i]['manufacture_id']; ?>
``` or
```php
<?php echo $order->products[$i]['manufacture_name']; ?>