I'm not sure what you mean by "outputs are enclosed".
But I too have 3 tanks - the two that everyone else has are on the drivers side under the compartment door (is that what you meant by "enclosed"?). The handle on the left is black tank, the handle on the right is the grey.
the Handle all the way over on the passenger side, about a foot away from the muffler - that's the shower grey water tank drain. Pull that one last, but it too drains out the one tube that you hook the sewer line to.
Clear as mud?