Sorry please, Baron,
Did not have the dimensions on hand that day...
I only knew that the early cutout is 4.5 centimeters in height, the late 5.5 cm
... or the relevant equivalent in inches.
The width is always the same (at least almost); about 18 cm (something) if I remember that correctly from my memories.
Or ... if you don't like metrical systems... 18 divided by 2.54 = 7.09 inches.
Yes, that fits quite well with your numbers...
Oops, depth of the radios...?
The usual Beckers are ... almost as deep as wide (almost quadratically) with mounting frame; so about 6-7 inches.
And the knobs distance? A little less, perhaps 14 cm (5.5 inches).
On the other side ... I have one "newer" Becker Europa" from the late 70ies, which does not work. And that unit is shorter, like the simpler Blaupunkts.
I can look that up for you if you like.
Achim
(Becker Europa TR)