drawn through a paper element filter (mounted externally on the right hand side of the hull), filtered air being distributed by a duct running around the perimeter of the interior at roof level, extending into the driver's compartment. Provision is made to add carbon filters in case of gas attack, and the system can accommodate heaters and/or air conditioning units. A roof-mounted relief valve allows a constant minimal pressure to be maintained and prevent ingress of foreign matter in the event of blast or alterations in external atmospheric pressure. Wading screens and a trim vane were fitted as standard and an extension provided to elevate the exhaust pipe. The basic vehicle, which could be readied for wading in approximately five minutes, has a water speed of about 6 km/h when converted for swimming and was propelled by its tracks. Most of these vehicles have had their amphibious capability removed. FV432s in service with infantry battalions are equipped with a pintle-mounted L7 GPMG (if not fitted with the Peak Engineering turret). Vehicles with the Royal Artillery, Royal Engineers and Royal Signals were originally fitted with the L4A4 variant of the Bren light machine gun, but they now use the GPMG. When equipped with the GPMG, the vehicle carries 1,600 rounds of belted 7.62mm ammunition; when carrying the Bren LMG, the vehicle carried 1,400 rounds of 7.62mm ammunition (50 magazines, each holding 28 rounds). There are two three-barrel smoke dischargers at the front. The Australian Army evaluated two pre-production FV432s during 1962 and 1963, but decided to purchase M113 armoured personnel carriers instead. The trials undertaken in Queensland demonstrated that the M113's performance was superior to that of the FV432. A number of surplus vehicles were sold to the Indian Army after being withdrawn from UK service. Variants The FV432 has been produced in three major variants, the Mark 1 (with a Mark 1/1 minor variant) with petrol engines, the Mark 2 with a Rolls-Royce K60 multi-fuel engine and the Mark 3 with a diesel engine. The Mark 2 minor variant, the 2/1, has its NBC pack flush with the hull side. An uparmoured variant, for use in Iraq and Afghanistan, of the Mark 3 was known as Bulldog. This name now appears to be extended to all Mark 3 versions of the FV432. The FV432 has proven to be flexible in use and can be converted from one role to another