Jon_a_its:
Resicast & Cromwell do as well
While the Resicast conversion is OOP, it was also designed for the Tamiya kit, not the AFV Club kit John has.
And Cromwell? Well, I'd recommend searching forums like Missing Lynx, Armorama, Track Link, etc. before directing anyone to that company. While they make some seriously nice items, you hear the horror stories about bad customer service and non-delivery of goods (besides, Cromwell's is a complete kit and not a conversion). Problems with Cromwell go back years. Here are some words from the ones who've been burned recently. Search these sites and you will find similar posts that are years old (2000 was one of the earlier ones I found).
http://www.armorama.com/modules.php?op=modload&name=SquawkBox&file=index&req=viewtopic&topic_id=167398#1406195
http://www.network54.com/Forum/409173/thread/1290980106/Cromwell+Models
http://www.network54.com/Forum/47209/thread/1281406114/Paging+Gordon+Brown%28Cromwell+models%29