Scale: 1/125
 
Recommended for the Lindberg 1/125 scale “Blue Devil Destroyer” USS Melvin DD-680, Fletcher class, built as a post-war ship.
 
The US Navy Mk.56 Director was part of a gun-fire control system (GFCS) intended to direct the fire of 3"/50 caliber dual purpose guns but was also coupled to 5"/38 mounts and 40mm Bofors mounts, from the 1950s through the Vietnam War.

Features:
accurately scaled director mount with bolt-head and access panel clasp details
separate, detailed base stand to allow the modeler to choose rotation
separate, detailed radar to allow the modeler to choose elevation
 
These 3D-printed acrylic parts are designed to accurately represent features of the actual ship based on official Navy blueprints.  These are not 3D-printed copies of Revell's plastic kit's parts and therefore are not the same size and shape.  Some adjustment to your plastic kit's parts or other aftermarket parts such as photoetch may be necessary for best fit.  CA "super glue" will bond this acrylic part to your plastic kit's deck.

© Model Monkey LLC.  This 3D-printed product may not be copied or recast.
 
The Mk.56 director was designed at the Massachusetts Institute of Technology (MIT).  It had an effective range of 30,000 yards and could track bombers at speeds up to 630 miles per hour.  Among the many warships it fitted to were battleship USS New Jersey BB-62, aircraft carrier USS Yorktown CV-10, and heavy cruiser USS Salem CA-139, now preserved as museum ships.

From Wikipedia: "The US Navy's Mk.56 Director "...was an intermediate-range, anti-aircraft gun fire-control system. It was designed for use against high-speed subsonic aircraft. It could also be used against surface targets. It was a dual ballistic system. This means that it was capable of simultaneously producing gun orders for two different gun types (e.g.: 5"/38cal and 3"/50cal) against the same target. Its Mk 35 Radar was capable of automatic tracking in bearing, elevation, and range that was as accurate as any optical tracking."

USS New Jersey: In the 1968 upgrade to the USS New Jersey for service off Vietnam, three Mark 56 Gun Fire Control Systems were installed. Two on either side just forward of the aft stack, and one between the aft mast and the aft Mk 38 Director tower. This increased New Jersey's anti-aircraft capability, because the Mk 56 system could track and shoot at faster planes."

Aircraft Carriers: Several Essex class and Midway class carriers received this director as part of their "SCB" modernization in the 1950s and the Forrestal class carriers are thought to have had them when built.  For example, from "Warship's Data #5 USS Yorktown (CV-10): "When modernized in 1953, the YORKTOWN received four MK 56 GFCS systems to control the 3-inch/50 caliber guns....It was a dual-ballistic system capable of issuing simultaneous gun orders to two different sized batteries and, therefore, could also be used to control the 5-inch/38 caliber guns."  This director is known to have been operated by:

Cruisers: Known to have been installed on USS Long Beach CGN-9, and Baltimore and Des Moines class cruisers, including USS St. Paul CA-73, USS Boston CAG-1, USS Salem CA-139, and USS Newport News CA-148, for example, carried four Mk.56 Directors, two straddling the forward superstructure and two aft. 

Destroyers: Also carried by several destroyers classes when armed with 3-inch/50 caliber guns, including Fletcher, Sumner, Gearing and Forrest Sherman classes, among others.  Fletcher class destroyer USS McNair DD-679, for example, carried this director (see photo above).