I have a mint condition Grundig Type 701 GDO s/n 3023, sold here in
Australia sometime in the mid-to-late 50s by Jacoby Mitchell. Works
really well, recently used to check some IF transformers.

I'm a bit curious about how widely sold these were, how many are still
in captivity.

It is *not for sale* but I can supply a .pdf of the original (in
English) manual, if you need one.

John Mackesy VK3XAO