When the Navy needed to replace its existing fleet of light, carrier-based photo-reconnaissance airplanes, it traditionally modified an existing fighter. The F2H-2P and F9F-8P were followed by the F8U-1P.
In addition, Vought improved the area ruling of the airplane. There had been considerable concern before the first flight of the prototype F8U fighter when wind tunnel testing showed transonic drag to be higher than had been predicted. Vought hadn't paid much attention to the newly discovered area-rule concept up until then and hastily developed a set of modifications to refine the fuselage shape in accordance with it. One or two were actually incorporated prior to first flight, as a result of which it was discovered that the wind tunnel data was not correct and the F8U's long, slim fuselage was close enough to an ideal overall cross-section increase and decrease.
However, with area ruling in mind, Vought tweaked the F8U-1P fuselage cross section, bulging it both upward and outward between the cockpit and the wing, in part to provide a flat bottom to the fuselage (also see the profiles in the picture at the beginning of the post).
The upper forward fuselage faired into a larger overwing fairing.
The inflight refueling probe, which had been added to the fighter in a large blister aft of the cockpit as an afterthought, was now fully enclosed within the fuselage. A window was added to the underside of the nose cone for a viewfinder so the pilot could accurately position the airplane for photography. The pilot could switch between two lenses, one with a narrow angle for use with the forward-facing camera (station 1) and the other, a wide angle for use with the cameras at stations 2, 3, and 4 which took pictures downward and sideward.
The instrument panel was dominated by the viewfinder.
Like the F8U fighter originally, the first F8U-1Ps had Vought-furnished ejection seats. These were replaced by the Martin-Baker seat, probably during the very late 1950s or very early 1960s. See http://thanlont.blogspot.com/2011/02/transition-to-martin-baker-ejection.html
The F8U-1P's fuel capacity was increased by 224 gallons over that of the F8U-1 fighter by extending the main fuel cell downward into the volume provided by the elimination of the rocket pack and adding a small fuel cell forward of the main fuel cell. This provided a significant improvement in mission radius and endurance.
The F8U-1Ps were redesignated as RF-8As in September 1962. Seventy-three of the original 144 were rebuilt between 1965 and 1970 to add an uprated J57 and ventral fins; these were designated RF-8G and retained their original BuNos. (Five Marine Corps RF-8As reportedly got ventral fins early; high-speed directional stability was marginal without them.) At least some got the later wing with hardpoints for external stores and wiring changes for an ECM pod.
A subsequent upgrade in 1977 resulted in a change to the more powerful J57-P-420, which required the addition of the external cooling intakes on the upper aft fuselage; there was, however, no change in the designation.
Various ECM antennas were added to the vertical fin over time, including a large forward-facing one.
For a walk-around photos by Chris Ishmael of an RF-8G with the external AB-cooling intakes in a museum, see http://www.cybermodeler.com/aircraft/f-8/rf-8g_walk.shtml
For some illustrations from the flight manual, courtesy of the Marine Corps Aviation Reconnaissance Association, see http://www.mcara.us/F8U-1P_RF-8A_design.php
There are no kits of the F8U-1P/RF-8. In 1/72 scale, there are vacuform conversions from Falcon and Airmodel and resin conversions from Ventura (see https://hangar47.com/rf-8a-crusader/) and RVHP; only the RVHP kit includes decals and its accuracy is questionable. There is a review of the 1/72 Final Touch conversion parts and Tasman decals here: http://modelingmadness.com/review/viet/mansrf8.htm.
As far as I know, only the Falcon version is readily available. See http://www.falconmodels.co.nz/kits.html
In 1/48, see Tom Weinel's post in Hyperscale HERE.
Last, but definitely not least, Fisher has released an excellent RF-8G conversion for the Trumpeter 1/32 kit. See http://fishermodels.indiemade.com/product/rf-8g-photo-crusader-conversion-132