there are 2 screws inside the bed right nere the tailgate vertical in the cornors.
There is no OBD connection on a 1990 Nissan as that is an OBD1 vehicle not OBD2. However there is a way to read the codes. https://codes.rennacs.com/Petrol-Engine/Japanese-Korean/Nissan-Engines.php
1342
Open the tailgate. About 5" back from where the tailgate closes, there are two 10mm screws on the edge.
A 1990 Nissan pickup truck has power steering. If the truck is displaying symptoms of not having power steering check the fluid levels and pump itself.
It'll fit, but it probably won't work very well, as a 1996 transmission would be wholly electronic, and the 1990 transmission would not.
The Nissan 4x4 pickup 2.3 was produced from the years 1990 to present in the United States. The spark plug gap on a 1986 Nissan 4x4 pickup 2.3 is .044.
underneath passenger side seat
In the ac box
your head gasket is probaly blown.
Go to www.installdr.com .
To remove the tail light on a 1990 Nissan 240SX, first open the hatch and locate the screws securing the tail light assembly; typically, there are two or three screws. Use a screwdriver to remove these screws, then gently pull the tail light assembly away from the hatch. Disconnect the wiring harness by pressing the release tab and pulling it apart. Finally, ensure all connections are secure before reassembling the tail light.
Probably not.