I don't know that the 87' is exactly the same but it probably is. I have an 83' 500sl. The instrument cluster is only held in place with a rubber seal around it. You need to gently lift up on the dash above the instrument cluster and insert your fingers in between the dash and cluster, then gently tilt the cluster forward while pulling out. Don't pull to far as there was not a lot of slack in the cables and wires on mine. I did this while I already had the steering wheel removed. I don't know if you can get it out without removing the steering wheel. Now once its out, unfortunately I could not find any way to get the front panel off. However on the back you will find that the intruments are actually in three sections. There are several small hex head screws around the edge. Remove these. Also there will be a few of the same type screws where the guage sections overlap, these will need to be removed also. I believe the center section overlaps the to outside guages so you will probably have to remove them all to get to the left hand section. The job sounds alot bigger than it is. While I had mine out I cleaned everything and replaced all of the bulbs. It looks like the day it came from the factory.
Hope this helps.