[projectRDM]

The lower harness plugs into the underhood fusebox.

89-90 cars uses the same plugs as the 91-94 cars, but the harness is physically different since the alternator and power steering pumps are on opposite sides.

The 95-98 cars use a different harness with different plugs, they will not work on any S13 chassis.

Additionally, auto and manual versions differ per year as well. In fact, the 97-98 lower harness is even different from 95-96s since the later models use a 4wire rear O2 sensor, not the early 3wire.

Viewing an FSM for each chassis will tell you all you need to know.