New Guy here need help with W140 S600 Transmission

[WaldS600]

First off I must say, I love this site for the great technical info. I have recently picked up a 1991 European model S600 with 86 km on the clock (basically about 54k miles)

I had a few problems initially with loss of power and poor shifting. With the help of this site, I did the following

1- oil and filter change
2- new plugs
3- new k&n intakes
4- fluid and filter change for the trans
5- new cats (old ones were plugged very badly)

After all of that, the power seems to be back. I do get an intermittent ASR light but that I will deal with after

The main problem is the transmission. Before fluid and filter change, the transmission would flare quite badly between gears. After fluid change, it seemed to grab well. Reverse was fine, and forward gears seemed ok. It would still flare slightly and it would seem to skip gear 2 and 3. It would feel like it was going 1st to 4th and the shifts were quite hard

After a few days it seemed like I was getting a little leak from the pan. I used new gaskets, but I was getting a slight drip. After a few days, it seems like my transmission won't engage gears at all. It will shudder when trying to select D, 3 on the shift gate. First gear seems to work, but every other gear is like neutral.

When I hit bumps, it sounds like I can hear the gear linkage disconnected? There is a heavy rattling around underneath the gear lever area. I know my bushings are absolutely shot, but would this be any cause or perhaps not being able to select any gears?

I have read most all the transmission threads. I have not checked for vacuum leaks, and I read about a stuck kickdown switch, but it seemed fine.

The shop now is telling me that I need a new transmission which I find slightly unusual at such low kms. There were no shavings or anything when I dropped the pan to change the oil. Then again the car is 15 years old.

After I found a little leak, I tried filling it with a bit more ATF, but now it seems that I am leaking a lot more fluid and it is smoking on the exhaust.

All help with all this would be greatly appreciated!