1. When it is necessary that there be an abatement of the shares of the distributees, they shall, subject to the provisions of the will, abate, without any preference or priority as between real and personal property, in the following order:
(1) Property not disposed of by the will;
(2) Residuary devises;
(3) General legacies;
(4) Specific devises.
2. Subject to the provisions of the will, and to section 473.623, devises of the same class shall abate proportionately.
3. If the provisions of the will or the testamentary plan or the express or implied purpose of the devise would be defeated by the order of appropriation and application prescribed by subsection 1 hereof, the property of the testator shall be apportioned in the manner found necessary to give effect to the intention of the testator.