Audio Systems: replacement speakers, screw holes, paper cones

Question
Hello Kelly,

I hope you can help figure this out.  I have a 1970 Mercedes Benz 280 SEL and desperately need to upgrade the stereo.  The problem is that I have an original restored car and do not want to cut the interior panels to accomodate the new speakers.

So, I went online @ Crutchfield and found some 4x6" speakers.  However the factor featherlite paper cones I pulled from the back dash of the car measure 80x190mm(3x7.5"), with the screw holes measuring 70x170mm(2.75x6.75").  

Am I missing something like,"the sizes are nominal.", or do I indeed have an odd size of speaker.  Please help me keep this vehicle original.

Thank you for your consideration.
B-

Answer
I think those will be hard to find, but all is not lost. You can make some easy adaptors with balsa wood or plexiglass and a scroll saw.
Just make an adaptor that use the original mounting holes, and then adapt whatever speaker (smaller) that will work. Hopefully, you have lots of room underneath and can mount the speakers in a suspended manner.