As I recall, GM was reported to have an unfunded pension liability in the neighborhood of 10-15 *billion* dollars as far back as the eighties. This during a time of robust sales. No one seemed to wonder then why none of the profits were being plowed into this snowballing liability.
Gonna have to look at Delphi's next monthly report to see if there's any more charges against their Pension fund to know how concerned to get, I guess.
As I recall, the IRS disallowed any "overfunding" of pension plans as that was deemed to be the hiding of profits. Maybe someone with more knowledge of these matters will clarify.