Z51 diesel engines and earlier design choices

Can the later Z51 engines support an earlier diesel-destroyer alternate history?

The argument relies on their older design foundations and an earlier divergence from the Reichsmarine's steam-turbine choice, while acknowledging that the specific production form came later.

The specific form of the Z51 machinery was produced for destroyers in the 1940s. The earlier alternate-history proposal rests on a claim that its underlying engine designs had existed since the late 1920s or early 1930s. A 1926 Reichsmarine decision to follow the steam-turbine route is identified as the procurement choice that prevented earlier pursuit of that diesel path. Changing that decision provides the proposed point of divergence. The scenario therefore distinguishes older design foundations from the later completed installation, without claiming that the finished Z51 machinery already existed in the 1920s.