The grey tank is the one to the passenger side of MH. It was set up to have a threaded rod which attaches to the valve and has a handle on the other side, to the left side of the dump pipe on the driver side to the rear. These valves can be ordered with or without a handle attached. I think that if you go to Inland RV web site, there are pixs of the two types of valves. All of my valves and dump connections are the older size of I believe 3.25" OD as probably yours are. Some of the valves are hard to find. The black tank valve is to the right of the dump pipe and the handle is short as that is where the tank is located. On mine, this valve pull has locking straps when closed. If you can not find the pixes on Inland site, try Thetford site. But again, beware the older units, pipe and connecting pieces are white in color and slightly larger the the new black connections.