An interesting thread this one and nice to follow but a post earlier up the list mentions the little square under the 60 of the tachy ring being later, this means my 6000 black/blue? dial proof/notch serial 06 shouldn't be like this then
All my 600x's are rebuilt using original parts in the main. My 6005 is virtually original though other than crystal and the best of my few.
A couple may have AM tachy rings, perhaps this is one as it's very well coloured without fade to the blue or red yet some scratches suggesting age.
My notes on them were lost in a burnt out PC so memory doesn't reach back to what had to be done to each of them.
JimW saw a gold one once at Ryton and felt sure the dial is AM based on the sub dial markers.
Don't want to hijack this silver topic thread, just some thoughts coming to mind as I follow.