The gauges-mystery continues..
By now, i have found out 2 things:
-The Ammeters we speak of still do not have a part number I could trace. They ARE 70A-0-70A, and rare as can be.
There seems to be only 1 model, 60MM, black face,chrome bezel.
I was wondering whether these were uniquely supplied with people with car phones, as part of a Tekade pakage.
Looks like that is not a correct assumption.
-The ext temp meter has always been available in 52 and 60MM, aftermarket
-If you check this link:
http://www.w124performance.com/docs/mb/articles/500E_Mercedes_Classic_Feb-2010.pdf..you find a report on a 6.9 that was sold, even though it was some form of a prototype, equipped with (non-available/non listed) seat belt un-tensioners and our 2 gauges.
This means that the "red 0" 60MM aftermarket VDO was clearly a factory install, at least in the very beginning, maybe longer.
Somewhere between 1977 (the date of that W116 prototype) and 1989 (ending R107), Mercedes stopped using the "red 0 VDO, black bezel" and decided to develop/order a special mercedes-only VDO with white 0 and and black bezel.
Question is when that was.
I also found out that the temp meters always seem to have had a black bezel, as far as the few available photos go.
I only found 1 photo where the bezel is in chrome, but there's still a chance that that was black painted, peeled off. I've seen others where that was clearly the case..
I also saw a photo where the 0 seems to be in white (with a black bezel) Regrettably, not a convincing photo quality.
But, the bezels at VDO are always interchangable between black and chrome, available cheaply.
The bezel color may just have been a non-issue for MB at the time.
Still...2 MB gauges with 2 colors bezels. It clearly happened, but how is it possible they didn't care?
Hopefully Thomas can clear this up. He has both gauges, and thus the part numbers.