GVT-04, taken at the PanzerMuseum, Munster, in 2006 by Marco Folin
In 1974/75, two full-size VT twin-gun prototypes were built by MaK. VT1-1 was built using Leopard 1 components and twin 105 mm armament. VT1-2 was converted from a Kpz70 and had twin 120 mm guns. It is currenly at BWB Koblenz (or was in 2013 at least).
In 1975/76, five Gefechtsfeldversuchträger (GVT, battlefield test-beds) were designed and built for further testing of the mobility and the basic concept of such a machine. These were much smaller than the VT1-1 and VT1-2. GVT 01-05 were only fitted with dummy guns and laser fire simulators. This concept was a potential replacement for Leopard 1, and was developed in parallel with Leopard 2. The GVTs used Leopard 1 running gear, but don't have much else in common.