Underhizzle

I just bought a 1984 5.0 mustang 5 speed today .... i didnt really get a chance to look at it that good... but when i cranked it.... it made a noise sounded like the flywheel was loose or something.... it was a real loud like clanging noise so i stopped right away..... Im going to put it up on jacks tomorrow and see whats wrong.... But was wondering if anyone had any ideas or had the same problem before..... Thanks.