The NC-8A is a land-based vehicle designed to provide external electric power to aircraft for pre-flight or maintenance purposes. It saw extensive service on the U.S. Navy Air Stations and Marine Corps Air Stations from the early 1970s and until the early 2000s. Note that the NC-8A unit was not a tractor; it was not designed to tow aircraft. Neither was it intended for shipboard use, being strictly land-based.
This 1:72 scale model kit, produced by F4Models (cat. # 7025), contains resin and photo etched parts to build one NC-8A vehicle with an option allowing to open up the rear compartment that houses cable reels and is visible when the vehicle is powering up an aircraft.
For reference purposes, here are some historical photographs that show the NC-8A in action: photo, photo, photo, photo.