The Delphi Retirees Pension Restoration Act aims to significantly increase the benefits guaranteed to eligible participants and beneficiaries of specific pension plans. It mandates that the Pension Benefit Guaranty Corporation (PBGC) determine guaranteed monthly benefits based on the full vested plan benefit , overriding ERISA's phase-in and maximum guaranteed benefit limitations. This measure specifically targets six identified Delphi-related pension plans, such as the Delphi Hourly-Rate Employees Pension Plan and the Delphi Retirement Program for Salaried Employees. For those whose benefits were previously calculated, the PBGC must promptly recalculate these amounts and adjust future payments. Additionally, the PBGC is required to make lump-sum payments within 180 days for past-due benefits, including an amount for foregone interest calculated at a 6 percent annual rate. Eligible individuals are those in pay status or eligible for future payments whose current benefits do not exceed their full vested plan benefits, excluding certain union top-up agreements. Funding for these increased benefits and associated administrative costs will be drawn from the unobligated balance of the PBGC's basic benefits fund. The bill also addresses the tax treatment of these lump-sum payments, generally allowing them to be included in the taxpayer's gross income ratably over a three-taxable-year period, with provisions for taxpayer election and special rules for death and surviving spouses.