The WZ-551 (Type 90) was developed into WZ-551A. It's estimated that less than 100 units of WZ-551 (Type 90) were produced. Despite being used as a common chassis for many different platforms, the total number of vehicles of all types entering Chinese service is small due to its engine problem, and with the exception of the basic APC version, no other versions of ZSL-90 is known to be successfully exported due to the same reason. Development continued, and the vehicle was planned as universal chassis for a variety of weaponry platforms, such as command vehicle, anti-tank missile carrier, self-propelled anti-air system, and armored ambulance. The finalized WZ-551 was certified with military designation ZSL-90 or Type 90 infantry fighting vehicle, which was fitted with ZPT-90 25 mm autocannon (similar to the turret of ZSD-89-II infantry fighting vehicle). In 1990, the WZ-551 was certified with the original 25 mm autocannon. However, further NGV-1 development was cancelled due to the imposed arms embargo in 1989. The new vehicle was named NGV-1, with N for " Norinco", G for " GIAT" and V for "vehicle". The French system has a night-vision system, stabilized gun, and advanced fire control system. Due to the urgent need to meet the schedule, the GIAT 25-mm autocannon was airlifted to China, as opposed to delivery via cargo ships, the usual practice at the time. In 1988, a deal was made with French firm GIAT to incorporate a GIAT 25-mm autocannon as the primary weapon for WZ-551 and the work on the redesign of WZ-551 began in China even before the French gun was delivered. In 1986, WZ-551 was confirmed by Central Military Commission as the future PLA wheeled platform, beating the internal competitor WZ-523. Plans were also made for an extended 4×4 and 8×8 vehicle family. In 1986, two more prototypes were sent to northern provinces and southern Hainan island for cold and hot-weather trials. In 1984, the cooling system and transmission system finished testing. To save development time, technologies from other Chinese vehicles were ported into the WZ-551, such as the sighting system, ventilation system, overpressure NBC system from the Type 86 IFV, 25 mm autocannon from the ZSD-89-II infantry fighting vehicle, and electrical water discharge system from the Type 63 amphibious tank. WZ-551 project pressed on and produced several prototype vehicles with different armaments. ZSL-92 of the Myanmar Army, armed with 25 mm autocannon WZ-523 project was then refocused for export effort and did not enter large scale service with the People's Liberation Army (PLA). However, it was discovered that WZ-523 chassis cannot meet the required performance standard. It first appeared on the 35th National Day parade in 1984. Due to utilizing old technologies, WZ-523 was developed much faster with initial production, starting in 1983.
Īnother project, WZ-523 based on the domestic Dongfeng EQ245 truck platform, was developed in parallel with WZ-551. The final choice was to develop 25 mm autocannon for the IFV variant and 12.7 mm heavy machine gun for the APC variant.
In 1982, multiple weapon configurations were proposed, including 35 mm autocannon, 30 mm autocannon, 25 mm autocannon, 12.7 mm heavy machine gun, or reverse-engineered 2A28 Grom from Type 86 infantry fighting vehicle. Production licenses for key technologies were acquired from Mercedes-Benz and Deutz AG. In 1981, WZ-551 finished prototyping proof of concept designs, and the vehicle was an indigenous chassis based on the imported Mercedes-Benz 2026 truck. WZ-551 was developed with the experience gained from the development of the WZ-521 wheeled armored personal carrier based on Jiefang CA-30 truck. The WZ-551 project began in 1979 and was the first wheeled infantry fighting vehicle developed by China.