...the 10R140 transmission has internal physical differences depending on whether it is paired with the 6.7L H.O. Power Stroke diesel or the 7.3L gasoline engine.
Key differences include:

• Planetary Gears: The diesel version uses four-pinion planetary gear sets in two of the four planetary assemblies, whereas the gas version uses three-pinion planetaries in those locations. The additional pinion gears provide greater strength to handle the significantly higher torque output of the diesel engine.
• Clutch Plates: The diesel transmission has additional clutch plates in two of its clutch packs, providing increased clutch holding surface area to better manage the diesel engine's high torque.
• Programming/Control: The diesel version of the transmission is controlled by a Transmission Control Module (TCM), while the gas version is controlled by the Powertrain Control Module (PCM), with different programming to optimize shifting for the respective engine's power band and torque characteristics.

The main difference is that the 10R140 transmission is a more robust, heavy-duty unit specifically designed for the higher torque of the 6.7L HO diesel engine, while the 7.3L gasoline engine in the same application is paired with it, likely as an added durability measure. The 10R140 is built to handle the diesel's torque, which is why it's also the transmission used in F-350 7.3L trucks. For the 7.3L, it is essentially an upgrade, as the base 10R100 is still a capable transmission and the gas engine does not produce the same level of torque.