ceiling replacement

[tom]

We purchased an older (1973) single wide with a metal roof. need to replace ceiling in living room. Tore down some of the damaged panels. There are what looks like 2x2 's with a strap between. Can i attach a metal 2x4 to these to give it strength and then put up sheet rock? A few of the supports sag slightly and i want to give them support.
thanks
Tom

[Ben]

I've got a 1984 or 85' Commador. It looks almost like the ceiling is separating in
the center. If I knew how it was put together, I should be able to fix it, but the
roof does'nt seem to be made of wood trusts. Could you give me an explanation
of the construction.
Sincerely Ben,