I want to make sure you don't do something drastic before proper diagnosis.
Yes the evaporator is a common problem, but that does NOT mean that your evaporator is the problem for sure. Before you get involved in this massive job, MAKE SURE THAT THE EVAPORATOR IS LEAKING. Use UV dye or a leak detector to absolutely CONFIRM that this is your leak. There are lots of other places that can leak.
I just want to make sure you don't get carried away since the thread went off in the direction of the dreaded evaporator problem.
My 124 car also has one of the problem evaporators, but it has been in there fifteen years now and still does not leak. It is very easy to fall into the trap of replacing a part because it has a bad reputation and is a known problem. It's one thing if it is $2.00 part that you can change in fifteen minutes. It's quite another if it is $300 part that takes over two days shop time to replace.
Look before you leap.