The YW-381 self-propelled 120mm mortar system is basically a Type 64 120mm mortar mounted inside the troop compartment of the Type 63 (YW-531) armoured personnel carrier (APC). The mortar is fixed on the floor of the APC's troop compartment, and can not move in traverse. Mortar tube elevation range is from 45~80 degree. The mortar crew are accommodated in the fully armoured troop compartment. A round window is on the roof of the compartment for mortar firing. The barrel muzzle reaches out of the compartment to reduce the blast effects on the mortar crew. Auxiliary weapon includes a Type 59 12.7 anti-aircraft machinegun mounted on the roof of the vehicle. NORINCO also developed the YW382 120mm self-propelled mortar, which is based on the improved Type 85 APC carrying a Type 86 120mm mortar. Both systems were developed for export market only and did not enter service with the PLA.