Development of an ARV based on the chassis of the Pz 61 MBT began at Thun in 1961 with the first prototype being completed in 1967-68. After trials with this prototype a modified version based on the chassis of the Pz 68 was placed in production. First production vehicles, known as the Entpannungspanzer 65 (or Entp Pz 65) were completed in 1970. The vehicle is fitted with a main winch with 120 m of cable and has a maximum capacity of 25,000 kg, which can be increased to 75,000 kg with the use of snatch blocks. The auxiliary winch used to pull out the main cable has 240 m of cable. Mounted at the front of the vehicle is a hydraulically operated dozer blade which is used to stabilise the vehicle or for dozing. Pivoted at the front of the hull is an A-frame with a maximum lifting capacity of 15,000 kg. A full range of tools and cutting equipment is carried. The Entp Pz 65 has a crew of five and a loaded weight of 38,000 kg. Armament consists of a single 7.5 mm machine gun and eight smoke dischargers. Upgraded Entp Pz 65 vehicles are designated the Entp Pz 68/88.