All three harvesters and the top two tanks have gas release. Where is the gas coming from? The hunter has it on the shoulder but I have never found it on the others. I had posted this on another post then realized that post was four months old.
The Harvesters and Tanks do have gas canisters, I think they’re on the sides of the “head” on the Tank, and atop the forward legs of the Harvesters, facing outwards. They can be shot off, though I don’t know if that actually disables the gas.