Are you speaking of the cover for the rear fan (evaporator housing)? Or
the section immediately in front of it?

If the evaporator housing is what you are referring to, it should still
be available at the dealer. There was a change made to the housing and
you might need to accomodate the change. I got mine (from the dealer)
about 4 years ago, and then installed it myself (oh, such fun).

If you are referring to the second just in front of the evaporator
housing, you should be able to get that from the dealer as well. To
install that one you'll have to take off all the sections in front.

Water dripping on the rear pad can be a simple matter of the
condensation hoses being clogged or disconnected from the inner
evaporator housing. In either case you'll have to pull it down (partly
at least) to correct the issue.