The job IS a big deal on the 124 chassis cars. If everything goes really well it will take 15 hours MINIMUM.

The job is documented very well in the Mercedes CD and I would NOT tackle the job without it. You could do it blind without the information, but you will probably ruin a few pieces in the process and make lots of frustration for yourself.

No, not ALL evaporators on these cars fail. My 88 300E has 18 years and almost 300,000 miles with the original evaporator. I have a friend with an earlier model 124 car who also still has the original. A part will get a reputation for failure when it fails in more than 10% of its installations. I don't know what the percentage is in this case, but it is certainly above the 10% number.

Have a great day,