[carlisleglass]

Here's the coding so it will work in v4.1.x branch (and its a lot easier, no need to edit any PHP files). I can confirm it works in v4.1.6 (Latest version).

1) Edit skin1/product_thumbnail.tpl and replace its contents with:

{* $Id: product_thumbnail.tpl,v 1.19 2005/11/17 06:55:36 max Exp $ *}
{if $config.Appearance.show_thumbnails eq "Y"}

	{if $manufacturer && $tmbn_url eq ""}<img src="{if $full_url}{$http_location}{else}{$xcart_web_dir}{/if}/image.php?id={$manufacturer}&amp;type=M" {if $image_x ne 0} width="{$image_x}"{/if}{if $image_y ne 0} height="{$image_y}"{/if} alt="{$product|escape}">
	{else}
		{if $thmb_url}
			<img src="{$tmbn_url}">
		{else}
			<img {if $id ne ''} id="{$id}"{/if} src="{if $tmbn_url}{$tmbn_url}{else}{if $full_url}{$http_location}{else}{$xcart_web_dir}{/if}/image.php?type={$type|default:"T"}&amp;id={$productid}{/if}"{if $image_x ne 0} width="{$image_x}"{/if}{if $image_y ne 0} height="{$image_y}"{/if} alt="{$product|escape}" />
		{/if}
	{/if}
{/if}

2) In products.tpl add the following code just before the } at the end of the {include file="product_thumbnail.tpl" statement :

manufacturer=$products[product].manufacturers