its official: doing dashboard replacement next weekend

[RG5384]

Someone may remember me talking about replacing the dash in my 83 300SD a couple weeks ago, well now it's official. Afterschool next week i will go look for my replacement dash, any tips anyone can give on what to look out for so my dash doesn't crack again in a month? The surgery will take place next weekend, and based on the recomendation from a friend, i will be replacing the diaphrams that you can only get to with the dash off, as well as the seal so my ac doesn't fog up my windsheild. Anyone know the part numbers on these or where to get them? I'm actually looking forward to this project. I will be taking pictures, and if i see an interest i may be able to be persuaded to do an entire write up of how its done, complete with pictures. wish me luck!
Ryan