The Versuchsträger 1-2 (abbreviated to VT, meaning "test-beds" or "experiment carrier") were two German prototype twin gun turretless main battle tanks. Since the early 1970's, a number of West German companies have been working on conceptual designs for a successor to the Leopard 1 main battle tank. This project had the name Kampfpanzer 3 (KPz 3). The KPz 3 project was temporarily a British-German joint project, until the U.K. withdrew because they wanted a turreted tank. The Germans had already developed the Leopard 2 and therefore didn't see the need for another conventional tank. One of the companies involved was MaK, developing the VT 1-1 and VT 1-2. The test program ended proving that a twin-gunned turretless tank could be created with enough technical effort, but had drawbacks in both practical and tactical use.