Cracked dash pads are a common W116 affliction and among the hardest to fix, since replacements are NLA; the accepted remedy is professional crack-fill and re-dye, with JustDashes and Bud's Benz named as specialists (or a protective cover as a cheaper stopgap). Interior wood varied by chassis number, with mahogany interiors paired to Zebrano/dark walnut trim on later cars.
Dash cracks and interior wood
Mercedes-Benz S-Class (W116) · cosmetic