I did almost exactly the same thing with my 1980 300D. I put in a new CD player, and front speakers. I see you don't have the dash grille cover on! What, are you saying they don't fit anymore? That's the problem I had! I had to mount them from underneath. It took forever and was difficult to work from underneath the dash. I didn't put any speakers in the back yet, as I was thinking of putting in 6.5" instead of 5.25", but I'll probably need to cut bigger holes first. You're right when you say the sound is better!
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