Goodman Games

Okay, I'm back, but now asking for Level 3 Mods that can easily be done in a 4-hour session. Thanks!

Bride of the Black Manse is designed for this, and is excellent.

The Star Wound of Abaddon is another excellent choice.

So "Tomb of the Savage Kings" is a 2nd level mod which easily fits into 3.5 to 4 hours. You could easily bump the HD, AC, and to hit scores to turn this into a 3rd level adventure.