I still have my P1747 code. I was told by another source as well that the instrument cluster was the problem. It has occasionally exhibited all manner of erratic behavior including freezing or going dead while driving, flickering lights, twitching gauge needles etc. but 95% of the time it’s OK.
I have looked into replacing mine with a used instrument cluster but have hesitated because it will display the odometer reading of the original car which won’t agree with the title and it will be as old as the one I have and just as prone to flaky behavior. The problem is usually caused by a bad capacitor on the cluster but I can’t see any obviously bad ones on mine. Some, but not all, of the clusters fo the W140s are the same as the R129 cluster (and there were many more W140s made so they are easier to find) but you must check which ones are compatible with your VIN and model year.
The frustrating thing is that the car drives fine, but this code, which is completely unrelated to emissions, has kept me from getting it smog checked and now my registration has expired so I need to do something quick. Good luck.