The Fairlady accessories crate can be found at the base of a plateau near a town in Silver Canyon.
Nearing the part will trigger a sonar beep, and will increase in rate as the player nears the part. Collecting the part, once prompted, will deliver it to Rav's garage on Airfield 73.
The player is required to complete the Mac: League 73 questline in chapter 2 - Desert Winds and collect the Fairlady chassis, before they can collect the engine & drivetrain.
Collecting the accessories crate will deliver it to Rav's garage on Airfield 73.