Who makes the Ford f250 transmission?

Ford's F-250 trucks use transmissions made by several different suppliers depending on the model year and configuration. For many years, Ford's heavy-duty trucks used transmissions primarily sourced from Ford itself, though the actual manufacturing might be done by a supplier contracted by Ford. More recently, they've also utilized transmissions from ZF Friedrichshafen AG. There's no single, consistent answer. To know for certain which manufacturer built the transmission in a specific F-250, you need to know the year of manufacture and possibly the specific trim level.