As you know, the Leopard 1 was not the first tank of postwar Germany. Germany work on different new tanks. There are prototypes as medium tank Indienpanzer (later developed into a Swiss KW30 and its successors Pz.58 and Pz.61), light tank RU 251 Prototype SpPz mit 90mm BK, early prototypes of the Leopard-1 MBT. On some forums I've seen mention about a strange Argentinapanzer - stage between Indienpanzer and prototypes of Leopard-1. However, I have been unable to find the details about this tank. It's definitely not a TAM, TanqueArgentinoMediano is subsequent and is not related to the Leopard-1.
Theory looks pretty good, after all, Germany and Argentina were close military-technical cooperation.
Does anyone know about Argentinapanzer, a german prototype tank for Argentina from the 1950s?