Does the car have ASR? If it does, I would avoid it.

If the wiring harness has not already been replaced it will almost certainly need that done. The part is cheaper for the M119 V8 than it is for the M104 six.

Evaporator core failure is the ticking time bomb on these cars. Some of them never fail. Some do. Hope that yours does not - it's impossible to predict when and if it will happen.

Cooling system must always be kept up to snuff as the motor is really wedged in there. The fan clutch is a very expensive ($500) part. The radiator is not expensive and is easily replaced when the time comes.

Besides that $%&*#!!! fan clutch the only other parts that are more expensive on the 400E than the 300E are brake calipers and the A/C compressor - they are very expensive but you can purchase rebuilt calipers. Whenever you need a new A/C compressor you're stuck if you have the Nippondenso one as it is pricey.

Other than these "gotchas" I honestly believe the W124 400E is one of the finest all around cars MB has ever produced. Mine has 145K miles now and still drives like a brand new and very expensive car. You'll get surprisingly good gas mileage, and that M119 V8 will run essentially forever if you don't overheat it and change its oil.

Good luck and post pics. Wonderful car the 400E.