To David & Wambli,
Going off Shan's update and Elena's alt fix, the only way I found this would work in 4.0.16 would be to do the following:
1. Create a new .tpl file called product_thumbnail2.tpl
/product_thumbnail2.tpl:
Code:
{* $Id: product_thumbnail.tpl,v 1.14 2004/06/24 09:53:29 max Exp $ *}
{if $config.Appearance.show_thumbnails eq "Y"}[img]{if $tmbn_url}{$tmbn_url}{else}{if $full_url}{$http_location}{else}{$xcart_web_dir}{/if}/image.php?productid={$productid}{if $file_upload_data.file_path}&tmp=y{/if}{/if}[/img]{/if}
2. Find "product_thumbnail.tpl" in related_products.tpl and change reference as below.
/modules/Upselling_Products/related_products.tpl :
Code:
{include file="product_thumbnail2.tpl" productid=$product_links[cat_num].productid image_x=0}
PS "image_x=0" allows you to display size-variable thumbnails
David