1989 Nissan D21 5 speed transmission is named?

The 1989 Nissan D21 5-speed transmission doesn't have a single, universally used name like a model number for a specific transmission. Nissan used different 5-speed transmissions in the D21 depending on the engine and options. To find the specific transmission in your truck, you'd need to:

* Check the transmission case: There will be a casting number stamped on the transmission case itself. This number is the most reliable way to identify the transmission.

* Check your owner's manual: If you have the original owner's manual, it might specify the transmission type.

* Look up your VIN: Using your vehicle identification number (VIN), you can often find detailed specifications, including the transmission type, through a Nissan parts website or a VIN decoder service.

Without any of that information, it's impossible to give you a name for the transmission.