* A727 (Torqueflite 3-speed automatic): This was a very common automatic transmission in these trucks.
* Getrag 360 (5-speed manual): A popular manual transmission option.
* NV4500 (5-speed manual): A heavier-duty 5-speed manual, often found in higher-spec or heavier-duty versions.
To know for sure which transmission is in a *specific* 1991 Dodge D250 4x4, you need to check:
* The VIN: The Vehicle Identification Number contains information that can decode the transmission type.
* The data plate: Located typically on the driver's side doorjamb, this plate lists key specifications, sometimes including the transmission.
* The transmission itself: Look for markings on the transmission case.
Without more information about the specific truck, it's impossible to say definitively which transmission it has.