Hi Ed,
The original speaker in the dash of the 113 was typical of the era for mono speakers--junk. Like tires, speakers have a shelf life that is more affected by temperature, sun exposure and age then anything else; it is near impossible to preserve these things. Consider them wear items.
While it was hard to source for some years (I think Bud's did take a single small speaker and create a mounting plate to fit the space)a few years ago Becker started making them again. Last year, they introduced their second generation of this reproduced speaker; Ed Ebel tells me it is superior to the one I bought in 2001 from Becker.
So once again, if you have any questions on this contact Ed Ebel at Becker.
Regarding Stereo, I think Doug Kim has nice "original" small speakers that sit on the left and right kick panels. I've never heard of what size these are or anything or whether anyone still makes something like this, but for someone looking to improve to stereo without a lot of metal work, this might be the answer.
Someone also once told me to just get a good boom box and put it in the space behind the seats! The space is not good for too much else (well, a fire extinguisher and some small items), and you can then lock it in the trunk when you are done! No cutting, wiring or welding or anything like that--and probably very cheap. Easy to remove for a concours as well!
Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored