The stock speakers are 4" in the front (dash top mount). The early 190E's had the same ...
The stock speakers are 4" in the front (dash top mount). The early 190E's had the same 4" in the back and the grill size will tell you if that's the case. Later models had 5.25 fitted. There was an optional amplified subwoofer system that powered door speakers also. If you are going to keep the 4" dash speakers, be sure to filter out the bass signals via an inline capcitor to the + terminal of the speakers. Larger rears are possible, but they won't be flush mount.