More likely than not, the engine will outlive the car itself as it would have rusted away to nothing.
Rust in floor panels, sills, doors and around the firewall
Cracks in chassis around firewall
Smoke
Bottom end noise
Transmission failures
Sagging suspension in sedans and wagons due to heavy towing
Carburettor fuel leaks
Warped disc brakes
Collapsing seats
Flat spots in hard acceleration