The initial Australian M113A1 FSVs were fitted with a turret taken from the Army's Alvis Saladin armoured cars. This was intended to be an interim design, used until an air-portable AFV was purchased. The turret was armed with a 76 mm L5A1 gun. One .30 calibre machine gun was mounted coaxially and another on the turret roof. Trials were conducted from 1967 to 1970. Trials were also conducted through 1968 with the American M551 Sheridan light tank. Concerns were raised regarding the safety of the combustible cases of the main gun. These were found out to be unsuitable so 15 M113A1 FSVs were purchased. A second batch of 45 vehicles were purchased in 1978 mounting a Alvis Scorpion turret armed with the 76mm L23A1 gun. The most important note for these vehicles was their successful deployment during the Vietnam war. The vehicles were used in the defence of fire bases, general convoy escort, night patrols and ambushes.
Over in America in June 1967 the Sheridan entered service with the 1st Battalion, 63rd Armoured Regiment. Over 200 Sheridans were shipped to Vietnam, but losses were heavy during normal operations, largely due to land mines and anti-armour weapons. In one incident alone, in March 1971, five Sheridans from the 11th ACR were lost in one day to RPG fire; all five vehicles burst into flames and were totally destroyed. There were also grave concerns regarding the engine system and the US Army took the decision to withdraw them from service in 1978.
In 1980 The Marine Corps initiated the Mobile Protected Weapon System (MPWS) program. In 1983, the Naval Surface Weapons Research Centre Laboratory mounted a 105mm gun onto a Sheridan. At the same time as part of its Rapid Deployment Force concept the US Marine Corps was testing the Canadian version of the 8x8 Piranha. One vehicle similar to the Australians was the AVGP program. Whilst the American military favoured the 105mm gun over the British 76mm gun, but as usual, the bean counters won the day and a full transfer of the 155mm gunned Sheridan turret was authorised to be inserted unto the Piranha hull. These vehicles equipped the US Marines, 10th Mountain, 82nd Airborne and 101st Airborne.
As part of the deal for the Canadian and Australian LAV program adapting the Scorpion turret for their FSV and a Fox turret for the IFV the British 16th Airmobile Brigade and 3rd Commando Brigade were allocated theCVR(W) to their respective regiments of the Household .Cavalry.
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