You can change the sold out image to whatever image you want, and it will be automatically resized according to the default product image size.
Just see the pictures, and you'll get the idea.
Installation is as simple as it can be, just open this, find that, after that add this, and it's done. No files are overwritten, no complicated database queries, no trouble at all.
If you need any help, free installation is on its way. Just contact me by leaving a comment, or via forum's PM (GoGo OpenCart).
OpenCart versions supported: All 1.5.x (see the notice at the bottom)
Extension's page: http://www.opencart.com/index.php?route ... on_id=4730
NOTICE: As soon as I test it with other versions of OpenCart, I will update the compatibility list, so stay tuned

