It is commonly recognized that the 5R55E/S/W transmission series is significantly less robust than the 4R70W. The stock 5R55S/W has marginal reliability when coupled with the stock 4.6L V8. Since I'm planning to increase the flywheel horsepower (fhp) of a 4.6L by replacing the 2 valve heads with 4 valve heads and possibly boosting the engine, I'm looking at transmission upgrade options. In 2006 Ford upgraded the Explorer from the 5R55S/W to the 6R60 transmission probably to complement the higher fhp 3 valve V8. Since the 6R60 bolts up to the 4.6L I decided to investigate replacing the 5R55S/W with a 6R60. I searched the forum and found a few threads questioning the possibility of the swap but nobody had tried it. I then searched the internet hoping to find a Mustang upgrade. There were lots of threads discussing the swap but nobody had actually tried it. The 6R60 is Ford's version of the ZF 6HP26 used in Audi, BMW, Jaguar, Land Rover and Maserati vehicles. I suspect the main obstacle preventing others from incorporating it in older vehicles is the interface to the PCM. The 5R55S/W has discrete electrical lines from the shift, pressure control and torque converter clutch control solenoids to the PCM. The 6R60 has an internal transmission control unit (Mechatronic) that controls the solenoids. The Mechatronic interfaces to the PCM via the CAN bus. I assume that the Mechatronic receives engine data from the PCM and transmits transmission data to the PCM. With the 5R55S/W transmission user gear selection comes from the Digital Transmission Range (DTR) sensor as a 4 bit binary code. The frequencies of the output shaft speed (OSS), turbine shaft speed (TSS) and intermediate shaft speed (ISS) sensors allows the PCM to determine shift scheduling, torque converter engagement schedule, and pressure requirements. With the 6R60 the same sensors provide the data internally to the Mechatronic which makes the schedule and pressure determinations. The 6R60 external interfaces pass thru the bulkhead connector located at the rear of the transmission on the right side. Below is a diagram of the connector followed by the pinout. Pin Signal name . 1 Series line . 2 CAN low . 3 ISO K . 4 not used . 5 not used . 6 CAN high . 7 not used . 8 not used . 9 TCM Terminal 15 (wake up signal) 10 "P" signal (starter inhibit) 11 not used 12 not used 13 TCM Terminal 31-1 (ground) 14 TCM Terminal 30 (supply voltage) 15 not used 16 TCM Terminal 31-2 (ground) Developing a 6R60 compatible interface would require modifying the 3rd generation PCM electrically to support the CAN bus and changing the proprietary PCM source code to match the 6R60 defined inputs and outputs. This is what Ford did in the 4th generation models to incorporate the 6R60. I have eliminated this as an option. Another possibility is to use the 4th generation PCM in a 3rd generation Explorer. That would require making all the other 3rg generation interfaces compatible with the 4th generation PCM and will be investigated in the future. A third possibility is to utilize the stock 3rd generation PCM and remove the Mechatronic and interface directly to the sensors and solenoids as is done with the 5R55S/W. The 5R55S/W case connector that contains the solenoid signals and the ATF temperature signal is located on the left side of the transmission behind the DTR sensor. The pinout is shown below. If it is determined that either of the above possibilities requires modification to the PCM source code (modifying calibration constants is allowed and does not apply) the option will be abandoned.