Production of the Pz Kw 1 Ausf A and B, Sd Kfz 101, ended in 1938. The Pz Kw 1 Ausf F was one of 2 developments of the original that came in response to requirements issued in late 1939 for further development. The result shared vrtually nothing with the original and entered service as the Sd Kfz 265.
Similarly with the Pz Kw II, SD Kfz 121, further development led to the almost completely unrelated Pz Kw II Ausf L which entered service as the Sd Kfz 123.
Pz Kw ... Panzerkampfwagen - a fully paid up tank
Ausf ... Ausfuhrung - model or mark
Sd Fkz ... Sonderkraftfahrzeug - special purposes motor vehicle
Any inability to detect the full logic of this system is not the responsibility of the Third Reich.
:grin: