I heard from someone who went to a recent judged event where he was told that ALL 1970 Mustangs had the window adjustment plate zinc or silver and should not be body color.
Guessing this was a MCA judging event but really doesn't matter. Very apparent that the person is mistaken and since they lumped all the plants together in the statement that may indicate how deep his or her investigation and understanding goes.
Also found this post where Jeff gives examples of everything but silver.
Of course that was just a look and discussion on NJ built cars
I've seen on unrestored cars the following Some much more than others depending on plant procedures
Body painted (on one side) plates mounted so that the body color is visible
Body painted (on one side) plates mounted so that the body color is visible
Black or bare finish face visible
Silver plate face visible One some - like San Jose - they appear to be painted silver not zinc plated
As mentioned in another thread I believe some of the painted plates may have been missed (placed in a location during painting where the painter missed) may explain some of the non-body color ones or if the worker dropped the body color plate during installation they may have had a tub of prepainted (body color) plates available so that they could quickly replace the dropped one to keep things on the line moving. This is likely IMO in those cases where we find one plat with no body color and the rest (1 or 3) finished with body color.
Hope posting examples from all plants in one thread gets confusing and generate cross talk. If it does may separate those discussions out by plant as usual
So for
70 San Jose built cars all I found so far is non-body color plates on unrestored cars
Looked at my collection of
NJ build unrestored cars and again came up with no examples with what appeared to be silver finish. Found just the typical and sort of expected body color paint finish and a few where they were rusty. Not sure if this indicates bare steel, thin coat of paint (body color or other wise.
And lastly
70 Dearborn examples
From an earlier thread. Vast majority found with body colored paint. Few silver and possibly black paint
Today's examples since your focusing on silver ones it seems I've left out all the body colored examples but did include (at the far right) the unpainted ones it appears. May be able to establish a pattern if have more time and its important at this time
Hope this helps