Been doing a bit of digging....
I saved a bunch of 63 pics on my pc a few years ago, when we were looking at buying ours, and checking thru some of the pics, it appears there is some variation on the position.
Whilst the pics are fine for selling a car they arent good enough resolution to zoom in to get a more detailed view, but I think they are clear enough to tell whether the mirror is above, between, below or on the two pieces of trim.
The first pic below is an unrestored MW car with original paint and panels, so I think it's fair to assume the mirror position hasnt been tampered with. You can see that the mirror (theyre the same on both sides but the passenger side pic I have is clearer) is between the bits of trim, ie mounted on the gold stripe.
The second pic is also an unrestored Ivory car (5000 miles!) that I think we can safely say the mirror hasnt been repositioned. This one shows the mirror is on the top piece of trim like ours.
The last pic is a car that was for sale when we bought ours ('only' has a 440, otherwise may have bought it!) that looks to have been restored. So whilst the mirror may not have been put back in the right place, it is now also on the top piece of trim. Would you change the position of the mirror during a resto unless you found it wasnt in the right place before you started? Hmmm... :thinker:
Maybe the position did vary depending who and which plant did the assembly? If the doors had pilot holes their position would be predetermined, but if they were screwed to the door on assembly without pre-made holes, they could have ended up in any old position, even if there were preset dimensions for them to use?
Who knows.... :icon_scratch:
Hope this helps! :icon_lol: