I disagree with the speakers comment. Its very difficult to find speakers that will fit properly in these cars and be well matched to the car. I would only suggest replacing them if: 1) There is a problem with them (buzzing, etc). 2) If the car does not have a sound system. and/or 3) You want to rewire the car and replace everything.

Otherwise, just replacing the head unit will yield a dramatic improvement in sound quality.

For early W126s (1981-1985), yes, replace the speakers... there are several nice 4x6 plate speakers that fit without major modification, and fit under the factory grills.

Later W126s (1986-), don't replace anything unless necessary. From the factory, these speakers are of reasonable quality and make good use of the enclosure they're in. For example, replacing the large round speakers on the rear deck is quite difficult due to their diameter. Aftermarket replacements are often very deep and hard to mount and seal properly. The amount of power needed to drive them, and air requirements around them, is very different. If you have a bad speaker, contact the dealer or Becker for a replacement... they're not as expensive as you'd think.

W126s with sound system (and W124s I think, not sure): You can identify these cars by the existence of factory door speakers. These cars have two amplifiers behind the back seat, one for left, one for right. The fader switch on the dash distributes the sound front/rear. So, the factory head unit only have a left and right pre-amp out. You can connect a modern stereo's preamp output to this connection with excellent results. You can make an adapter, or buy from from Becker Auto Sound. You've noticed a significant improvement in quality of sound by just replacing the head unit!

W124s from 1994-1995 (and some other cars like R129s, etc): These cars are equipped with the Becker Active Bass system. You might notice the front door speakers don't do much... thats because they are actually only bass speakers. There is an amp in the trunk which handles the distribution to all the speakers. This is a speaker-level amp, and a new stereo can be installed by connecting the speaker level outputs directly to the original connections. Don't use a pre-amp output here.

Special note about 1991-1993 cars: Its been mentioned here many times before, but these cars have a two-piece head unit. The second part in the the trunk where the tuner and pre-amp/speaker outputs are. If you install a new head unit, you need to run lines from the back of the car to the front. Becker used to sell kits for this purpose, not sure if they still do. Note that these cars can have the two-amp setup as described above.

Many amps and speakers are available at Becker Auto Sound for all these cars, and many are not very expensive.

Remember: These are all future classic cars: The more modification you do to them, the more you effect their value. Personally, I wouldn't buy a car that had its factory sound system modified.

Jaime