The US Army received the M48A5 tank in the early 1970s. This index represented earlier tanks, chiefly the M48A3, upgraded to match the characteristics of the M60. The modernization consisted of installing a 105 mm gun, new fire control systems, new engine, improved cruising range, etc. Large scale modernization began in 1975 and touched about 2100 tanks. However, there were earlier attempts to modernize the M48 to the M60 standard, attempts that will be covered in this article.
M48A2 with the T254/X15E8 gun
This tank was never going to go into mass production. It was only used for trials, in this case trials of the new T254 (M68) 105 mm gun. For comparison purposes, the T254 was later replaced with the analogous British X15E8 gun. These trials took place in 1958-1959 during trials of the X15 and T256 guns for the new XM60 tank at the Aberdeen Proving Grounds. The gun barrels were interchangeable.
|M48A2 tank with the T254 gun. This gun made 35 shots before it was replaced with the X15E8. Aberdeen Proving Grounds, 1969.
|X15E8 (left) and T256 (right).
90 and 120 mm guns mounted in specialized turrets also took place in the trials. The T256 proved to be the best choice. It was sufficiently powerful and comparatively light.
Artillery Command asked the Ordnance Tank-Automotive Center to develop a project to modernize the M48A1 to the level of the M60 on June 10th, 1959. The new tenk received the designation M48A1E1 on April 21st, 1960.
The tank received the AVDS-1790-2 engine and CD-850-6 transmission, aluminium fuel tanks, and engine deck components from the M60. The gun was replaced with the 105 mm M68. The new tank carried 57 rounds of ammunition for it. The fire control system from the M60 was also installed.
The suspension was also changed. Most components from the M48A1 remained, but it had to be reinforced to make up for the extra weight. Only three return rollers were used instead of five. The tank with ammunition loaded weighed about 48 tons.
Six vehicles were converted in total. #1 was sent to the Aberdeen Proving Grounds in March of 1960. #2 arrived in Fort Knox on April 6th. #3 was used to evaluate the complexity of repairs and maintenance. #4 was sent to the Detroit Tank Arsenal. #5 and #6 were used in 1960-61 for extreme weather trials in Yuma (Arizona), Aberdeen Proving Grounds, and the Arctic.
Trials reports indicated that the M48A1E1 was identical to the M60 in everything except armour and surpassed all production M48 variants in mobility, cruising range, and armament. The report also noted that the M1 commander's cupola needs to be replaced since it was too cramped for installation of new equipment.
The OTAC decided to cut costs in November of 1960 and get rid of the 105 mm gun. The reason was that there was still a large amount of unused 90 mm ammunition in storage and production of 105 mm rounds was limited by the budget. Two M48A1E1 prototypes that were re-armed with 90 mm guns were indexed M48A1E2. After a few minor changes, these tanks were indexed M48A3 (Type A). The tanks converted from the M48A1 to M48A3 still had five return rollers per side.
A new modernization program was enacted on December 7th, 1965. This was essentially a revival of the M48A1E1 program, consisting of installing the M68 gun on the M48A3. Unfortunately, while the financial and bureaucratic aspects of the program were ironed out, all the tanks were either sent to Vietnam or already earmarked for use in that theatre.
- M48A2 with the T256 (M68) and X15E8 (L7) 105 mm guns, 1958-1959
- M48A1E1 with the M68 gun, fire control system, engine, and transmission from the M60, 1960
- M48A3 (Type B) with the M68 gun, fire control system, engine, and transmission from the M60, 1965
- M48A1E3 with the turret, engine, and transmission from the M60, 1965-1967
- M48A2C with the M68 or L7 gun, engine, transmission, and potentially the fire control system from the M60, 1966-1967
- M48A5 with the M68 gun, fire control system, engine, and transmission from the M60, 1975