Ford never offered the Mustang as a station wagon, but that didn't stop car modders from creating their own:
The story goes that in 1966 Italian coach builder Intermeccanica built a Mustang station wagon for advertiser Barney Clark and designer Bob Cumberford which showed up in many car magazines of the day. Supposedly Ford had a Mustang wagon in design stages around the same time but scrapped the program shortly after the Intermeccania cars appeared. The Intermeccania cars are often mistaken for a factory concept.
Pictured above is a non-Intermaccania conversion, currently on sale on eBay. You can view several more pictures at the link.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=290502683221&ssPageName=STRK:MEWAX:IT#v4-44 via Jalopnik