Old prunes can be replaced with a number of synonyms that can be used to describe something that is old and withered. Some alternatives to "old prunes" include "dried-up," "shriveled," "wrinkled," "wizened," "weathered," "aged," "decayed," "faded," and "fossilized." Each of these words captures the idea of something that is past its prime, having lost the vitality and freshness it once possessed. Whether describing a person, object, or idea, these synonyms can be useful in conveying a sense of age and decay, as well as nostalgia and a sense of history.