The Solunar uses a movement derived from older Venus calibres but is denoted internally as an ETA:

http://www.chronocentric.com/forums/heuer/index.cgi?page=1;md=read;id=37564

Ron, Jarl found some of the 1940s up-and-down (i.e. 6 and 12 o'clock configuration) chronos used Venus movements, so Heuer clearly did use Venus in the past. I wasn't aware of them using their movements as late as the 60s - I had just assumed those two register watches used the Valjoux 92 (which is available with a 30 min register as well as the 45 min version we are used to from those early Carreras and Autavias). But I guess it could be a Venus 186/7/8 instead.

Maybe you could encourage Luuk to introduce himself on the forum and provide us some pictures to peruse?