Interesting find find by RavenOne, from the book "Bell UH-1D »Huey«" by Robert Busse:
Licence-built UH-1D (serial: 64-13881 - 70+40) with Bell and Dornier, used by Daimler-Benz in 1969 as an experimental using the Mercedes DB720/PT706 twin-shaft turbine engine. This setup was planned for use on production UH-1Ds in the Bundeswehr inventory, but this never happened.