Question: When was the engine used in the Cromwell and Comet tanks discontinued?

Context paragraphs:
Rolls-Royce Meteor: The Rolls-Royce Meteor was a British tank engine developed in the Second World War.  It was used in British tanks up to 1964.

Cromwell tank: The Cromwell tank, officially Tank, Cruiser, Mk VIII, Cromwell (A27M), was one of the series of cruiser tanks fielded by Britain in the Second World War.  Named after the English Civil War leader Oliver Cromwell, the Cromwell was the first tank put into service by the British to combine high speed from a powerful and reliable engine (the Rolls-Royce Meteor), and reasonable armour.  However the originally proposed dual-purpose high velocity gun could not be fitted in the turret and the medium velocity dual purpose gun fitted proved inadequate.  An improved version with a high velocity gun became the Comet tank.

Detroit Diesel Series 51: The Detroit Diesel Series 51 was a two-stroke diesel engine built by General Motors, Detroit Diesel Division from 1951 to 1959.  Unlike other GM/Detroit Diesel engines, the 51 series designation did not refer to the cylinder displacement, but rather to the year it was introduced.  Two versions were produced, an inline two-cylinder (2-51, 108 cid ) and an inline four-cylinder model (4-51, 216 cid ).  This was accomplished by using loop scavenging ports for both intake and exhaust along with a mechanical blower.  This engine used a dry sleeve with 9 intake ports and three exhaust ports in that sleeve.  These sleeves were located in such a way that the exhaust ports lined up with exhaust ports in the block that were physically higher than the intake ports in the block.  This resulted in pressurized cool air being forced through the intake ports just after the exhaust started exiting (note that the exhaust ports in the sleeves were higher at the top than the intake ports while the bottom of all ports in the sleeve are at the same height.  The net compression ratio is 18:1.  Unlike a two cycle gasoline engine, the crankcase was not used to draw in the fuel/air mixture.  Instead, the blower forced air in the intake ports and fuel was injected by a camshaft actuated injector which was pressurized by a gear pump.  As fuel is injected just before top dead center, little unburned fuel is expelled in the exhaust, unlike a two-cycle gasoline engine.  The elimination of exhaust valves reduced the complexity and weight of the engine.  The power output and RPM of this engine was controlled by governing the intake air and controlling the opening of the injectors with shutdown accomplished by completely closing off the air intake.  The much lower weight of this engine compared to engines with valves made it quite suitable for applications where other engines of the same horsepower were not feasible.  Its uses include: Marine propulsion, generators, pumps, air compressors, road graders and other industrial uses.  It was never factory installed for automotive purposes but conversion kits and engines were made available for automotive use.  This engine design did not see widespread use due to not being able to reduce the exhaust noise to an acceptable level, as any exhaust restriction would have resulted in a reduction of power and efficiency.  It was a very fuel efficient engine with a high power output to fuel consumption ratio.

Coffman engine starter: The Coffman engine starter (also known as a "shotgun starter") was a starting system used on many piston engines in aircraft and armored vehicles of the 1930s and 1940s.  The Coffman system was one of the most common brands; another was the Breeze cartridge system, which was produced under Coffman patents.  Most American military aircraft and tanks which used radial engines were equipped with this system.  Some versions of the Rolls-Royce Merlin engine used in the British Supermarine Spitfire used the Coffman system as a starter.  The Hawker Typhoon also used the Coffman system to start its Napier Sabre engine.

EcoDiesel: EcoDiesel is an engine used in the Ram 1500 since 2014, as well as in the Jeep Grand Cherokee.  Approximately 20% of 2015 RAM 1500s are equipped with the engine, mostly ones sold in Europe.  FCA uses the EcoDiesel name for two different engines.  One is the VM Motori A 630 DOHC 3.0L engine used in the Grand Cherokee, and Ram.  The other is a Fiat 3.0L diesel used in the Ram ProMaster.

Continental AV1790: The Continental AV1790 is an American V-12 engine used in tanks. Produced by Continental Motors, the AV1790 was used in a variety of limited production and pilot heavy tanks, including the M53 and M55 howitzers, the T30, T34, T43 (neither to be confused with the Soviet T-34 or T-43), T57, and T58 tanks, as well as the production M103 tank (derived from the T43) and the M51 recovery vehicle.  There were also diesel versions (AVDS, automotive vee engine diesel supercharged) for the M47, M48, and M60 Patton tanks.

Shelby Charger: The Shelby Charger is a modified 1980s Dodge Charger.  Carroll Shelby tuned the Dodge Omni-based Charger for Dodge from 1983⁄ to 1987, with the resulting car sold as the Dodge Shelby Charger.  When the Charger was discontinued, Shelby bought the last 1,000 and replaced the fuel intake and engine management system with the same high-performance one used in the 1986 Shelby GLHS.  It has a blow-through long runner two-piece intake, modified turbocharger (reclocked with a different compressor cover), and is intercooled.  This engine was rated at 175 hp and 175 ftlbf of torque from 2400 rpm to 4800 rpm.  This is similar to the Turbo II inline-four engine used in various Chrysler vehicles, but the Turbo II uses a forged crank, as opposed to a cast one, and a stronger Getrag A555 five-speed manual transmission is used in place of the A525.  The GLHS still came equipped with the rod linkage a525 transmission, however.  Shelby also changed the struts and shocks with Koni adjustable units, wheels from his own wheel company (Centurion 2s), and high performance Goodyear Eagle GT tires.  His modifications prompted the federal government to declare the car a Shelby model.  A "Dodge" badge appears nowhere on the car, unlike its five-door L-body sibling, the GLH Omni, which does have the Dodge nameplate.  Shelby Chargers were built at Chrysler's Belvidere, Illinois, assembly plant, with the GLHS models in 1987 being built at the Whittier, California, plant of Carroll Shelby.

Comet (tank): The Comet tank or Tank, Cruiser, Comet I (A34) was a British cruiser tank that first saw use near the end of the Second World War.  It was designed as an improvement on the earlier Cromwell tank, mounting the new 77 mm HV gun in a new lower profile and part-cast turret.  This gun was effective against late war German tanks, including the Panther and, at most ranges, the Tiger.  The tank was widely respected as one of the best British tanks of the war, and continued in service afterwards.

River Don Engine: The River Don Engine is a 1905-built steam engine used for hot rolling steel armour plate.  It is a 3-cylinder simple engine of 40 in diameter, 48 in stroke.  At its operating steam pressure of 160psi, it developed 12000 hp , and was able to reverse from full speed in 2 seconds.  The rapid reverse was an essential feature of an engine used for rolling, as delays would result in cooling of the workpiece.  This engine was one of four built to the same design, one going overseas to the Japanese Government, one to John Brown's Atlas plant, and the destination of the final one being William Beardmore of Glasgow.  It is claimed to be one of the most powerful steam engines ever built, and the most powerful remaining in Europe.

Honda Rafaga: The Honda Rafaga series CE4 and CE5 was a compact 4-door sedan sold only in Japan by Honda, introduced in January 1993, and used the same 5-cylinder engine that was used in the Honda Inspire and the Honda Vigor and shared a platform with the second generation CE series Honda Ascot.  "Rafaga" is Spanish for "gust" or "blustery".  The engine is installed longitudinally, the same configuration used in the Vigor and Inspire.  The Rafaga was third in Hondas hierarchy of sedans, and a sister car to the Ascot, which was sold at the "Honda Primo" dealership network.  The Rafaga was sold in Japan at "Honda Verno" dealerships, and was one level up from the Honda Integra.  As with other Honda products, the Rafaga used double wishbone suspension at the front and rear wheels.  The "2.5 S" trim level came with a front suspension upper strut brace in the engine compartment.  In Japan, the smaller G20A engine used regular grade fuel, while the larger G25A engine used premium grade fuel.

Supporting paragraphs: Cromwell tank Rolls-Royce Meteor
Answer: 1964