The torsion bar crossmember commonly rusts out. It is not a terribly difficult repair, but it is easier with the floor section out that normally need to be done with it. Look at the rest of the frame rails. If they are OK, this is no biggie, depending on your tools and skill. Also look at the inner rockers where this attaches.
They don't make them anymore so I'd try to fix it if it all possible. I certainly couldn't sell it to somebody like that unless they were fully informed. buyer beware your mileage may vary
