Rudy agrees to sell Jack his "like-new" Mustang, do they have a legally

Rudy agrees to sell Jack his "like-new" Mustang, do they have a legally enforceable contract?

Rudy and Jack have lived next door to each other for the past 15 years and are buddies. In his garage, Rudy has a 1964 Mustang that Jack has always admired. One day, Jack asks Rudy if he would consider selling the car to him. Rudy tells Jack that the car is in "like new" condition and is worth more, but since they are friends and he knows how much he loves the car, he will sell it to him for only $4,000. Jack tells Rudy, "You've got yourself a deal." The next day, Jack inspects the car more closely and realizes the engine is missing, something he never noticed before because he never looked under the hood and never saw Rudy actually drive the car. Jack confronts Rudy and says, "This car is worthless without the engine, and I don't want to buy it anymore. Rudy tells Jack that he wants his $4,000 or he is going to sue him for breach of contract.

Do they have a binding contract? Must Jack buy the car from Rudy, even though it doesn't have an engine? What factors determine if a contract exists and if it is legally enforceable on both parties?