From the FASA Star Trek KLINGON SHIP RECOGNITION MANUAL, circa 1985
D-7 (Various Names) Class IX-X Cruiser
Known Sphere Of Operation: Empire-wide use
Data Reliability: A (all models but D-7S); D for D-7S
Major Data Source: All but D-7S in Star Fleet possession; Klingon Sector Intelligence.
       The D-7M, introduced on Stardate 2/1105, was a match for the Federation Constitution and Romulan V-6 (Gallant Wing) cruisers. This gave the Klingon navy a slight advantage along its borders, and the Imperial Command began to press the balance more aggressively. Both the Romulan navy and Star Fleet commissioned upgraded versions of their vessels shortly after the appearance of the D-7M in order to hold the Klingons in check. Within two years after its introduction into service, 75% of all facilities producing the D-7A had been converted to manufacture the D-7M, allowing the Klingons to place more and more of these ships in sensitive areas. As the Klingons grew bolder, these ships began to appear in the Organian Treaty Zone and in the Triangle. Traveling in groups of threes, sorties were made by Klingon commanders into areas that were declared neutral or de-militarized, and several worlds were subjugated by small forces of these ships.
       The D-7M mounts the KWE-3 warp engine, which (in this configuration) gives more efficient power for maneuver and added power for the weapons systems; this warp drive system allowed the D-7to travel at Warp 8 and, in an emergency, Warp 9. The KD-6 disruptors were replaced with the more powerful KD-8s, extending the offensive range of the ship to 200,000 km. An additional improvement, giving a punch that surprised many Romulan and Star Fleet commanders when first encountered, was the KP-3 photon torpedo mounted both fore and aft. Improved shielding was also added, increasing its capabilities by 50%.
       Several vessels of this type, named "Bringer Of Destruction" from the Klingon K’t’inga, have gained a level of fame equal to that of the USS Enterprise, most notably the IKV Bardur. The Bardur is known to have destroyed over 20 Romulan vessels, 10 Federation vessels, and participated in skirmishes that have accounted for the loss of over 40 enemy ships. The captain of this ship has been promoted to Admiral and, much like his Federation counterpart, remains in command of his vessel, now the smallest ship in known space to be a fleet flagship. The current position of this fleet is in the Orion sector, operating from the border starbase located there.
       Of the 1,244 D-7M’s built, 965 remain in active service, 198 have been destroyed, 8 have been captured (5 by Star Fleet and 3 by the Romulans), 11 have been scrapped, 36 are in the service of ranking families of the Empire, and 21 have been reported as missing. Three of those missing were destroyed during the V'ger Incident, and several others are known to be operating in the Triangle under the command of renegade Klingons.
       The D-7R, named "Bringer Of Agony" after the Klingon K't'rika, was another attempt by the Klingons to make use of the plasma weapons, this time incorporated into the improved D-7M hull with the photon torpedo bays removed. The RPL-1 was placed in the bow of the ship and an additional KD-8 disrupter was placed in the aft compartment. In addition to these changes, a KCC cloaking device was added. The Klingons had learned by this time that the plasma weapon and cloak were designed to be used together, often by remaining cloaked and stationary in the path of their adversary before decloaking and firing the plasma bolt at minimum range.
       Of the 32 D-7R’s built, 29 remain in active service, 2 have been destroyed, and 1 has been captured by Star Fleet.
       The D-7S, the newest of this line of cruisers, is an improved version of the D-7M, appearing to be a D-7M at first glance. Only well-trained personnel will be able to tell the difference on a sensor scan, but these cruisers mount six KD-8 disruptors and fore and aft-firing KP-4 torpedoes. In addition, some models carry the KCC cloaking device.
       The D-7S, named "Bringer Of Justice" from the Klingon K't'mara, is being produced at the same facilities as the D-7M, which intelligence reports show will be phased out for this much-improved version; the facilities at Taamar, Gnuu Re', losia, H'rez, and Z'hai are producing 40 M models and 22 S models per year, Of he 66 D-7Ss built, 65 remain in active service and one has been listed as missing. Although Star Fleet has encountered these vessels, none have been destroyed or captured. Orion reports from within the Triangle suggest that the Klingons are operating several small groups there.