Some gearboxes might have clutches/flywheels, others wont... but most should have bellhousings... price will vary depending on whether they have those parts and the condition of the box.
Rallystanza, i dont think they will bolt right up to a 4agze, but it wouldnt be too hard to buy/rig up an adaptor plate.
Ive put down an order for 5 so far... now it just comes down to how quick they get shipped here.