Just got an instrument cluster for a 1981 300D at the local bone yard and wanted to know if there is some way to test the clock with it out of the vehicle. I have a 1982 300d which is slightly different.... mine has a tachometer added. Can I test this cluster in my vehicle?

There should be a male quick disconnect terminal sticking out of the back of the clock. That is your positive battery connection. Grounding can be provided anywhere on the metal chassis. You can use the clock feed from your mercedes or simply hook it up to a good battery (even a fresh 9 volt should work). If using a car battery put a 1/2 or so amp fuse in line to protect yourself and the clock in case of a short circuit. Hope this helps, John.