A huge number of M113 Armored Personnel Carrier variants have been created, ranging from infantry carriers to nuclear missile carriers. The M113 armored personnel carrier has become one of the most prolific armored vehicles of the second half of the 20th century, and continues to serve with armies around the world in many roles.
Some Australian AFVs have the suffix "AS" often appended by a model number, the "AS" is a NATO code for Australia.
Generally speaking Australian models are modified from the original models, in the case of the M113A1 series this included the AN/VIC-1 communications harness, large dust filters for the passenger compartment ventilation blower, heavy steel track manufactured by ADI, provision for 600 kg of belly armor, the Cadillac-Gage T-50 turret mounting twin .30 Brownings(early service) or a .30/.50 Brownings machine guns for APC/LRV versions, a traverse bar to prevent the crew commander traversing the turret to the rear over the troop compartment roof hatch with the guns depressed low. For some reason all versions of the M113A1 had the passenger compartment heaters removed except the M577A1 command vehicle. In the late 80s the fleet was issued with German BM8005 image intensifying night vision driving periscopes, which with the aid of an adaptor, could be fitted to replace the driver's central periscope for night driving. In the early 90s the fleet was issued with VINSON family cipher equipment, typically a single KY-57 per vehicle. This allowed the command net to be enciphered, but the admin net would normally work en clair.
- M113A1 Fire Support Vehicle (FSV) - Full designation Carrier, Fire Support, Full Track M113A1 (FS) Saladin Turret was a variant fitted with the turret from the Alvis Saladin armored car. The FSV was introduced into Australian Army units in the mid-1960s following the withdrawal of the Saladins and was armed with a 76mm gun, a .30 caliber coaxial machine gun and a .30 caliber machine gun mounted on the roof of the vehicle's turret. The M113 was an interim vehicle and was replaced by the M113 Medium Reconnaissance Vehicle in the late 1970s. It was commonly referred to by Royal Australian Armoured Corps crews as the "Beast".
- M113 Fitter - Armored recovery vehicle with HIAB (Hydrauliska Industri AB) crane on hull roof.
- M113A1 Light Reconnaissance Vehicle/APC - A standard M113A1 with a Cadillac Gage T50 turret as used on the V100/V150 series of armored cars, mounting two Browning machine guns, a .30 caliber and a M2 .50 caliber machine gun. While the standard armored personnel carrier version in Australian service is also fitted with the T50 turret it initially carried only twin .30 caliber machine guns. In later service the LRV and APC versions both carried the 30/50 combination and the only difference between them was roles. LRVs were used in sabre (recon) troops of the Cavalry regiment and the recon troop of the Armoured regiment. They carried a crew of 2 or 3 (crew commander, driver and sometimes operator/observer). APCs carried a crew of 2 and dismounts, either infantry, assault troops, engineers or other troops. In practise an LRV was also perfectly capable of carrying troops, though in perhaps somewhat more cramped conditions as LRVs often carried additional stores and ammunition and had seats removed and replaced with storage lockers. For a short period of time in Vietnam the Aircraft Armaments Incorporated Model 74C Cupola/Command Station was used, but it was quickly replaced by the T50. Also used by the New Zealand Army until the M113 was replaced in 2005. The T50 turret was initially fitted with an optical sight, however in later years this was removed and the guns were solely aimed using raging bursts of 6-10 rounds (2 tracer). The diesel burning heater is removed from the M113A1 - though numerous diggers note that this is not the case with the Australian Army's M577s (command post vehicles).
- M113A1 Medium Reconnaissance Vehicle (MRV) - Full designation Carrier, Fire Support, Full Track M113A1 (FS) Scorpion Turret was an Australian variant similar to the M113 FSV, but using the turret from the FV101 Scorpion light tank, instead of the older turret of the Saladin armoured car, that the FSV had previously used. This turret was equipped with an Image Intensifier sight for the main armanent. This II sight was the first effective passive night sight fitted to an Australian AFV, giving the MRVs a night fighting capability exceeding the Leopard AS1 and all other Australian AFVs of the period. Whilst fully amphibious, the MRV was also fitted with a light sheet metal foam filled trim vane and side pods. These pods and the trim vane were intended to provide additional flotation and stability ion the water, they provided virtually no additional armour protection. Other changes include a modified drivers hatch with pivoted toward the centre line of the vehicle instead of opening to the rear of the drivers hatch, this feature preventing the open drivers hatch being caught of the traversing turret, as well as the fitting of the British "boiling vessel" an electric vessel for boiling water and heating rations. As indicated by the designation change the MRVs were roled as reconnaissance vehicles and issued to the Cavalry (medium reconnaissance) regiments whereas the FSVs were originally issued to APC squadrons and used to provide infantry fire support.
The MRV replaced the FSV in Australian service
- M113AS3 - significantly upgraded M113 with new engine, drive train and brakes.
- M113AS4 - upgraded to the same standard as the AS3, lengthened to fit an additional road wheel station and fitted with a new Tenix Defence designed one-man turret with a heavy machine gun.