So my project today was to switch out a broken power window switch. Well while I had the door panel off, I noticed the speakers were shot (normal for the Sprinters) the foam around the paper falls apart. So I took out the old speakers and cut the plastic form from the back, this allowed me to use the factory enclose as well as the factory wiring! Turned out good.
These Sprinter speaker adapter rings allow use of bigger and better 6 1/2" door speakers without any door modifications for better sound without spending a lot more.