Back in the day, there were some brief periods in time where IBM deviated from the 'black' ethos of the original Richard Sapper IBM notebook design language. Sometimes it was for reasons which are clear and sometimes not!
Besides some early, cream Thinkpad 700 and 720 machines, the grey notes, Zenith's Thinkpad 300 and the Japanese-only 330, there were these strange grey 750-series machines.
In some of the official hardware manuals it lists some specifically 'grey' 750 machines and accessories for the German market. This may have been because in the 1980s and early 1990s, Germany had a government regulation what stated computer screens could not be enclosed in black or white plastic (although that rule had actually ended by the time the grey 750c was released). This was to ensure contrast for the viewer.
This didn't last long, as I say, because by about 1993 the regulation was abandoned and most future German Thinkpads reverted to black.
Another quirk to all this is that my grey 750c has a german FRU keyboard, but with grey UK British keys (with £, ' , / , # , <, > and 2/2) which are outliers relative to UK British keys. We think that perhaps IBM sold a UK key converstion kit to a very select number of customers.
Here is a couple of rare examples of the 750c.
