You've got me on all your questions.

It was pointed out to me by Weber Motors a Mercedes dealer in Edmonton, AB (about 1,000 miles from where I live). They have done some servicing on my car when I have been unable to do it and have been familiar with the car since about 1987.

This was in 1997 and I was preparing the car for a long drive to Ontario and back...about 12,000 kms. I had done my usual work...oil, filters, tires, shocks, etc and had recently acquired a low mileage 83 SD for parts. I was swapping out a bunch of stuff into my car which had 285,000 kms....trans, prop shaft and steady bearing, exhaust, diff, calipers, etc.

I then asked the dealer if there was anything else they could recommend and they commented on the timing chain saying that MB recommended changing (they might of said checking...can't recall for sure but I generally fix things ahead of schedule as I can't afford breakdowns) every 120,000 kms.