there are 2 screws inside the bed right nere the tailgate vertical in the cornors.
1342
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
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 .
quickly
Probably not.