i have a Blaupunkt Boston CD player/receiver.  Crutchfield told me it
wouldn't fit but i measured and bought it anyway.  it fits just fine, though
the rear of the unit sits on the air handler assembly (some folks may not
like that), sans a cradle of any sort.  it skips only on the the most
bone-jarring of bumps (or cabinet-opening bumps as i like to call them),
just like any other CD player.  and the opening in the dash was a perfect
fit.
i think the opening is of little consequence (height x width), rather depth
is what companies like Crutchfield use when determining fit, due to the fact
they supply "installation kits."  had a support of some kind been used, that
probably would have made it to deep for their installation kit.

or i could be totally wrong.
jason

82 Vanagon Westfalia