Even if this is an old thread, I will add some notes as I'm right now in the process of optimizing the cluster of my 1987 W124 250D, manual 5-spd transmission (European model).

- The first steps, before anything, is to get under the car. Unhook the speedometer cable from two clips located on the transmission. No need to disconnect the cable from the transmission. This will give the necessary "slack" to the cable, which will be needed to provide hand room to unscrew the cable nut at the cluster. Failure to do this may cause the speedometer needle to "jump" as the pulling force will yank the cable. If the undershield on the transmission area is in place, it will need to be removed to unhook the speedometer cable from the clips.

- Review and disconnect the clip which attaches the speedometer cable by the pedals' area. This will continue to provide the "slack" needed for the cable.

- Once the two steps above are done, then start using the cluster pulling tools. There are 5 clips that hold the cluster at the back, which are not visible. The cluster also has 4 rubber feet, 2 above and 2 below, which help both holding and sliding. To unstick the cluster from the clips, use a small flat metal spatula, carefully, in order to not damage the dash's tolex. This operation is intensive and requires quite a bit of care and patience.

- Because of the slack already provided to the speedometer cable, it should be much easier to pull the cluster out enough to use the right hand (left-side steering vehicle) and insert it behind the cluster to unscrew the nut holding the speedometer cable. (Before repositioning, spray lithium grease so that screwing the nut back in place will be much easier).

- What I personally did, before disconnecting anything, was to label each of the cables connected to the back of the cluster. This way I knew which bulb goes where it originally belongs. The 16-pin plug connector to the fuel/oil/temp gauges pulls out, but if it is the first time it will be firm enough, carefully pull it out.

- I removed the 4 clips that hold the cluster from the back. I am also in the process of optimizing the rough metal edges from inside the dash so that the cluster can slide out easier if further servicing is needed at a later time.

- Replacing the halogen bulbs with LEDs is a chore. While the overall lighting and bulbs from the right side (on sockets with cables) can be easily replaced (there are suitable bulbs available from SuperBrightLEDs), the ones from the signal green arrows and the warning indicators ("idiot" lights) on the left side use special halogens which are soldered to their bases (Osram 2721MF with B8.5D base). It required me to go on a search for the LED bulb with that specific base.

- Installation is the reversal. Make sure that all cables are connected and both 16-pin plug and the speedometer cable are attached. Push the cluster back into place, then do not forget to reattach the speedometer cable at the pedals and to the clips on the transmission under the car.