I am new to the forum, so first off, thanks for having me. I have a 74' 450SL with about 150K on the odo and the tachometer bounces like crazy. While cruising at about 65MPH, the RPM's are running at like 5000. IT idles at between 1000 - 1500 and I know that's not right! By the way, my speedometer and odo are not working. What's the deal with the tachometer though?