ANY HELP WOULD BE GREAT

I have a 2000 ML430 with about 127K miles that's had no previous issues. Until about 3 weeks ago when, while driving and using the electroic gear shifter to pass another car, the transmisson slipped. I backed off after I realized there was no power going to the wheels and the tach was climbing. Once backed off, the transmission seemed to catch it self and all was fine.

Well, that was until 2 days ago.

Again asme senario, passed a car down shifting from D to 4th, the tranny slipped and didn't catch until the car came to a complete stop and was put in park. I then started out going again very slow and the truck felt as if it was towing something - strong torque etc. I then pulled into a service station and was going to check the tranny fluid but of course found no dipstick. I called MB and they told me that my model year dosen' have one but the could sell me a tool - lot of good that does miles from the dealer! In any event, I purchased some tranny fluid and topped it off. Got going again to the house which was about 45 miles away and all seemed fine including the torque feeling was gone, but I wasn't about to try the electronic shift again!

All went well until I slowed to a stop to turn off the highway onto a local road. Once I made the turn I hit the gas and it went but would not go over 35 miles an hour and seemed to stay in 1-2 gear . I am told this was the MB Limp Home Mode. Well needless to say, I parked the truck as close to home as I could get and now have it towed to a local transmission shop. They have told me they pulled a few codes for the transmission and engine but I didn't get the specific codes from them yet. The started talking new transmission with out yet droping the pan and telling me if the gears have been thrown etc.

By now I have looked all over the web and learned a few things that could have happened but I need your help!

My questions are:

I know the planetary gears can be thrown do to breakdown in the bearing between them and the sun gear. Supposedly this was a comon issue with these transmissions. I guess once the pan is dropped We'll know what happened there, but I have also seen in some posts that there are solinoids that could have gone bad etc. What are these and which ones?

If the tranny was toast would the limp mode still work in reverse and drive?
(I noticed that I couldn't auto shift with the electroic shifter after all this happened and it was in limp mode.)

If I have to replace the transmission do I also need to replace the torque converter?

Was there an update done on these transmissions to fix the planetary gear problems? If so in what model year?
(According to MB tech all the trans are the same between 1998-2005 the only diffenence being the programing/software that runs them. So I likely have to change several things if I put a trany in from a later year into my 2000.)

Please any help would be great. I just want to make sure I dont pay for a new transmission and it end up being an electrical problem (solinoid) or a programing software issue etc....

Plenty of info on transmission failure here. Type in 'transmission failure' in the 'Search This Forum' box at the top right of this fourms page. Here is one example of what you'll find Transmission Life Expectancy

Well the problem was found to a failing shift solinoid. The valve body was pulled the cover removed and all solinoids were tested for resistence values. The shift solinoid was out of spec and was replaced for $388.00 (MB dealer part cost). This all makes sense since the problem occured when using the auto shifter mostly and only once when not. Hope this helps anyone. On a side note, the tranny was refilled with the MB "lifetime" fluid but was initially over filled due in part to many tech specs give different values for how much fluid to add. So heads up if you have a similar problem..... Thanks everyone for all the feed back.... Issue Resolved!