I pulled the cluster and all the gears for the speedometer/
odometer weren't slipping and seemed fine.
I then got under the car and poked around the transmission
area. I found the small metal (magnetic?) cylinder that goes
into the transmission had come out and was hanging by it's
wires. the screw that attaches this to the transmission was
missing. A truly easy fix!
Speedometer works fine now and I painted the
instrument needles while the cluster was out.
I am now a happy Mercedes camper.