Well..since nobody has an input so far here we go. I am an average DIY but, I have the manuals. I recently changed the evaporator in my 86 300E and I had to get the blower out as part of it. It is labor intensive but "doable". Without the manuals it is very difficult to explain since the wiper assembly has to come off, the middle section in front of the firewall has to come off, etc. I suggest you buy the manual(s), it is the best investment you can make for your car. The CD would pay for itself by doing this job alone.
Think about it!