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All I know is, if it's a diesel rig, make sure you get one built for diesels. The early diesels shredded the stock E4OD TCs over and over until they came out with beefed up replacements to handle the torque.
Or if that doesn't work, go to: http://www.bulkpart.com/
Click on "Ford Transmission parts", then "E4OD transmission parts".
They have some different performance converters listed for right around $250.
Good Luck.
Your local independent transmission rebuilder/shop should be able to get you a stock reman for a competitive price. That's the route I went with my old truck.
In the shop I work at we use Dacco converters which are about $70 for an E40D converter. You can also get performance converters from TCI or B&M but they are more expensive ( like $195 ).