When a unit is beyond economical repair, this is where the replacement starts.
Transmissions are identified by the build code stamped on the case, not by the model year. The same vehicle can carry two different units depending on engine, drivetrain and plant, and the calibration in the control module is written for one of them. A unit that is mechanically compatible but from a different code will shift harshly or set ratio codes.
Listings state the transmission code, the drive type and the engine it was built behind. Keep the original tag photograph when you remove a unit; it is the only reliable way to match a replacement.
