The exact type of the transmission is 722.650, but generaly known as the 722.6 series or 5WA 580.

Here is a dipstick:
http://cgi.ebay.com/ebaymotors/Mercedes-Benz-Transmission-Fluid-Dipstick-Tool-722-6_W0QQcmdZViewItemQQ_trksidZp1638Q2em122QQcategory Z35625QQihZ015QQitemZ250244336708QQrdZ1QQsspagenam eZWD2V

Don't be fooled by the length, as the end of the dipstick is not hitting the bottom of the pan, but is being held up higher, so difficult to make yourself (and not worth it as you can see the low price, I bought mine from $25).

Also make sure that you check the temp with a WDS/Autoenginuty reader to measure the temp, as the oil level needs to be checked at 80 degrees Celsius.

I hear more and more that the new fluid from shell used in the 7 speed boxes from MB could also be used in the older 5 speeds we have, but I have no confirmation yet, and personally would stick with the only approved one. The oil can be bought cheap at a Mercedes dealer, at least in the EU, don’t know what they charge for the dipstick though, as I also bought mine from the internet.

Andre.