An AOD from a fox Mustang should be cheap and plentiful, and the swap parts are readily available. I am by no means an AOD expert, so I'm not sure if an AOD from a Crown Vic for instance is physically the same as the fox version. I would imagine they are, but I would consult someone much more knowledgeable than me before I bought one.
BTW. You might want to swap cams in your explorer motor. It will work as is, but I have been told the stock explorer cam is not well suited for smaller lighter cars. Also, a lot of Explorers used what are called GT-40P cylinder heads. The difference being, the P heads have a different spark plug angle. (They stick nearly straight out rather than angled) Most vintage Mustang headers block access to the plugs, but there are headers made specifically for this swap. If you search for GT-40P you'll get some more info.