 Variants include a tractor-trailer truck, a dump truck, a fuel truck, and a 6x6 for towing a 4-wheeled powered trailer.The ZIL-131 also serves as a platform for the 9P138 rocket launcher, a 30-tube variant of the BM-21 "Grad".The ZIL-131 was introduced in 1966; it is a military version of the ZIL-130, and the two trucks share many components.