I did this on my 81 300td. Get the seal with the rubber or plastic-clad
outside because I was completely unsuccessful at getting the "plain" seal
inserted. Lots of belts to get off, bolts to remember to tighten, etc,
REMEMBER TO MARK THE POSITION OF THE DAMPER CLEARLY AND INDELIBLY! Also,
DON'T LOSE the metal slugs that hold the damper to the pulley. That is,
just be danged careful. Also, my manual shows using a brass tool so that
you don't nick the interior of the crank.
Other than that, can't think of anything. Putting it back on was a two
man job for me.
Anyhing else, feel free to ask!