Bought mine from NPD as well. The specific parts are about half way down the search results, but are all out of stock.
https://www.npdlink.com/search/products?search_terms=windlace&top_parent=200001&year=1973
Edit - looks like Ohio Mustang has stock
https://ohiomustang.com/store/order_page.asp?itemid=2108
Before posting this, I emailed KM and I was told the person had passed away.I was told the guy who was making them passed away. Not sure if someone else started making them.
I believe I heard that from NPD or it could have been thru Kentucky Mustang.
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