If your tractor is like ours, there's a diagram under the left foot rest as you're sitting on the tractor. Ours looks like this.
I'm sorry that it's so blurry, but it was a hard photo to snap. The garage is full, the mower decks on, and I'm too lazy to move junk, jack it up, and snap a proper photo.
Does your tractor's drive belt look like this? If it does, it the belt will look odd as if something's wrong due to the unique way the factory routed the belt.
I hope this helps. The photos are of a 1989 Craftsman II 18 HP 6 speed (3 speed hi/lo) Garden tractor.