In July 1966 the Philippine Civil Action Group - Vietnam (PHILCAG-V) recieved 17 M113A1 APCs along with other materiel from United States Military Assistance Command - Vietnam (MACV). These vehicles, some of which featured the Armored Cavalry Assault Vehicle (ACAV) armor kit, were to augment PHILCAG-V's security contingent and were used to conduct patrols and provide security for civic actions.
In 1970 the Philippines recieved a shipment of approximately 15 M113A1 APCs. Additional vehicles were supplied in 1976, 1978, and 1981. These vehicles, along with a small number of M41 light tanks and a number of Cadillac Gage V-100/V-150 armored cars comprised the bulk of the Philippine Army's mechanized equipment until 1980.
A planned M113 upgrade project for the Philippine Army involved the refurbishment of existing M113 APCs in the inventory to an M113A3 version. The scope of work included modernization of the automotive component, weapon system, communication system and survivability features. Singapore Technology Kinetics (STK) of Singapore won the initial contract to refurbish 3 units. The contract was abrogated due to deviation from the technical specification in the COR.
As of 2004 the project had been resurrected following an offer from FNSS of Turkey to refurbish 7 units and provide power packs to repower another 7 units for the same allocated amount. However, instead of bidding, the project would be pursued through direct negotiation under a government-to-government arrangement as offered by FNSS. The project was subsequently differed because of a lack of funds.
In 2007 the Department of National Defense - Armed Forces of the Philippines (DND-AFP), throught the General Appropriation Act and the AFP Modernization Program Act Trust Fund, approved 144 million Philippine pesos for the acquisition of 6 upgraded M113s or derivatives (any vehicle maintaining 80 percent or more commonality with the M113). FNSS of Turkey subsequently won the competition, but as of September 2008, the Philippines was still negotiating delivery of the vehicles.
Between 2006 and 2009 the Philippines engaged in a number of local upgrade projects for the M113, mostly for the purposes of upgrading the power pack and armament of the vehicles. Most basic of these upgrades was the replacement of the standard M2 .50 caliber machine gun with a Dillion Aero M134D rotary barrel machine gun, purchased under Phase 1 of the Philippine Army Capability Upgrade Program. In 2007 12 of these weapons were traded to the Philippine Air Force for unspecified number of M39A3 20mm cannons. These weapons had been removed from Philippine Air Force F-5 fighter aircraft, which had been permenantly grounded due to a lack of spare parts in October 2005. The weapons were mounted in an modified ACAV cupola and linked to the vehicles internal electrical system as a source of power.
A small number of vehicles were converted to a Fire Support Vehicle configuration using turrets removed from Alvis Scorpion light tanks, similar to the Fire Support Vehicle configuration used by the Australian military. Some vehicles also had Cadillac Gage 1-meter turrets removed from V-150 armored cars fitted. It is unknown whether these turrets were standard or variants upgraded by Floro International to accept the ST Kinetics 40mm automatic grenade launcher fitted to Philippine Army Simbas and the prototypes of the MX-1 Kalakian.