Stall Converter????

[Longhorn Man]

And to go a little more basic, it is located at the front of your tranny, and bolts to the flex plate(flywheel) ont eh engine. This item has (basicly) 2 fans in it, one driven by the engine, and the other facing the first, and driven from the rushing fluid. (place 2 indow fans one facing the other. Turn one on... the other will start to turn from the air moving through the blades)
This is the simplified explination of a torque converter. This way, you can keep it in gear with the engine running, and come to a complete stop without stalling the engine.
As stated above, a higher stall torque converter will alow you to bring the RPMs up more as you take off. Much like when you are driving a stick. If you want to take off fast in a 4 speed, you rev the eninge higher as you let the clutch out.
However, this is one thing that is more of a science, and if your thinking of getting an aftermarked unit, call the pros (like TCI) and have your vehicle weight, tire size, tranny type, rear gear ration, and engine specs on hand so they can sell you the right one.
The less you know about all those things and how they work together, the more important it is to call someone who does. If you get the wrong torque converter, your ride wil most likely be a dog and feel real 'slushey'.