A couple of more comments.

1) I know a MB shop that has been in business 40 some years. The owner contends that the MB fluid is simply synthetic transmission fluid. He has been servicing the 722 series transmission with non-MB synthetic since they came out. However, in this case, I elected to do it myself and use the MB fluid.
12 bucks a liter on the net. 7 - 8 liters. If I let him do it and the transmission goes south, he is not going to warranty the transmission.

2) The actually mechanical part of the procedure is easier than the procedure on my 300E. In particular the pan bolts, at least on my '97S320, have a machined part surrounding the bolt which removes the precision needed to get the torque exactly right. You tighten metal to metal and the
lip of this part is dimensioned to apply just the right compression on the gasket. The filter slides up and snaps in.

3) On mine I elected to replace the data plug (receptacle). The new one came with two white O rings versus the original part that had 1 black O ring.
Apparently, these are routinely replaced at the Dealer. My dealer had 18 in stock. $8.00 ea.

3) Dipstick. I don't think there is a shoulder that stops the stick. The bottom of the plastic tip bottoms out. Saw a post on some forum from a guy that made his own from , I think, plastic coated wire. The thing is that the correct dipstick tool is made to precisely fit in the tube. There are a couple of fairly good bends along the route to the transmission. Thats the reason for the coiled wire construction. I would be cautious about assuming you can attach a thermistor to the stick and actually get it down the tube. It's a tight fit. What if you get it down there and can't get it out. Now the logic of $40.00 saving will really come in to question.

Finally, I share the opinion of others. You are talking about a $4,000 + risk here. What is the point of pinching pennies on this procedure?

Steve