The Chinese Type 81 is a SPRL based off the Soviet BM-21 "Grad"
About this creation
The Type 81 is built off the Shaanqi SX2150 chassis, a 5 tone 6X6 heavy duty truck, itself based off the Ural-375 chassis.
The Type 81 came to fruit after the 1979 Sino-Vietnamese War between China and Vietnam. During the conflict, China captured several Soviet BM-21 "Grad" rocket launchers. As the Chinese did not have relations with the Soviet Union, they did not receive military supplies from the Soviet Union. So the BM-21 was completely new to the PLA.
With little effort the PLA was able to reverse engineer the BM-21, eventually producing the Type 81 in 1982 and was adopted for service the same year.
Due to the fact that it is a direct copy, the Type 81 is extremely similar to its Russian predecessor. Its tubes are mounted on a six-by-six truck, the same as the BM-21