We are selling our home and we received this report from the home inspector.

The home is equipped with two, gas fired, 50 gallon, State brand water heaters original to the home. We noted all four dielectric unions were corroded and show indication of previous leakages. We recommend the union be replaced, this may entail replacement of the water heaters themselves do to the extent of the corrosion. We also noted previous water leakage at the water shut-off valve on the left water heater and recommend the valve be replaced.

Is there a way to replace these four dielectric unions without replacing the entire water heaters?