I just did the K1 accumulator kit on my 95 E320. It had the famous 2-3 slip. It's not difficult to do. I bought the kit for $5 and dropped my trans pan and replaced it.
The 2-3 slip did get better. I also put in Mobil 1 at the same time, so I don't know whether it was all due to K1 kit.
If you have questions, let me know.