Bruce, my first Benz was an '80 300SD (w116) and I had removed the instrument cluster a few times. Actually there isn't anything holding the cluster in but friction. Remove the lower dash cover below the steering wheel. With this removed you can push the cluster from behind. It will come out enough for you to disconnect the speedometer cable, which just unscrews. There will be a circular elctrical connector to remove also. The thing to be careful about is the oil pressure line. You will need a 10mm wrench, actually 2 of them. Use one as a backup to prevent from ruining the fitting on the back of the guage. Everything else is self explainatory. One thing you also might want to do is disconnect the car's battery to prevent shorting anything out while pulling the wires off. Once out, you will see that there is a large ribbed rubber band (strap) that goes all the way around the cluster. This is what holds the cluster in place.
I hope this helps.
1994 MB E320 Coupe (199,500 mi)
1992 MB 190E 2.6 (173,000 mi)
1983 Porsche 911SC (148,000 mi)
2004 Volvo V70 2.5T (198,000 mi)
President of CT/Westchester Section