Morgans can refer to several things, and each of those things has its own set of synonyms. If you're talking about Morgan horses, you might use the words "thoroughbred," "stallion," or "equine" as alternatives. For Morgan dollars (a type of coin), you might use the words "silver dollar," "money," or "currency." And if someone's surname is Morgan, their name might be replaced with alternatives such as "Smith," "Johnson," or "Williams."
Ultimately, finding synonyms for "Morgans" depends on the specific context in which the word is being used. Regardless of the meaning, though, all of these synonyms can help make your writing more varied and interesting.