When I was looking for this there was almost no information, if this is common knowledge, I apologize.
The K1 spring for the 2-3 shift is a pretty common repair that has done a lot of good in a lot of peoples transmissions, Mercedes updated the K1 spring, the newer springs are more stout than the originals.
However there is no information for the 3-4 K2 Spring. I had some issue with the 3-4 shift so I wanted to try to replace the 3-4 spring.
I deal with a great parts guy at Crown Mercedes Benz and he did some research and came up with 2 different part numbers called K2 springs in the catalog. I think he found them in the 190E 2.3 catalog, if you look up a K2 for a 1987 300D nothing comes up.
Anyways, he got both in and I pulled the spring and holder out of my car. One of them matches.
Some people say the K1 is interchangeable for the K2. This isn't true of the transmission in later cars.
On the left is a new K1 kit. The two blue kits are the K2 kits Mercedes found, and the green on the far right is the K2 that came out of my 1987 300D.
The part number on the Green holder that came out of the car matches the part number on the light blue holder for the new K2 kit. The springs are identical in dimension, so Mercedes must have just changed plastic colors.
The part number on the tube is 126 277 84 32
However the kit part number is 126 270 04 35
The part number for the dark blue kit is 126 270 05 35 and the packaging says K2 on it so it is the K2 for some version of the 722.
The K1 part number is 126 270 44 77
Pan Gasket part number is 201 271 03 80 67
Transmission filter part number is 201 277 02 95