A 4R70W should be what tranny the truck has. I think ford just put a tougher gear set in them for the 5.4L engines. You should have no problem finding a shop that can work on it as they are extremely common in the ford world.

Hell its the tranny the mustang guys are beefing up for the street/strip drag cars. Even guys with 05+ stangs are replacing the 5r55s tranny with them because they are stronger and simpler to work on.