X-Cart forums - Parent Product Code for Variants on Invoices?

I thought I had seen a post about this somewhere but I have searched and searched and can't find it anywhere!

I have products which have loads of variants so the product codes for each variant end up being HUGE.

Does anyone know how I would go about getting the parent product on the invoices rather than the variant code.

For example:

I have a product set up with a code of F75_8085
A particular variant will have the code F75_8085210567 (a bit long!)

I just want F75_8085 to show up on invoices etc as that is the actual code I use to order from manufacturers.

I know it's in the skin1/mail/html/order_data.tpl template at this line that the code is displayed:

<TD align="center"> {$product.productcode}
</TD>

I just don't know what to change it too to show the parent code.

Pleeeeeeeeeeeeeeeeaaaassssseeeee help :)