The first thing I ask when someone is looking for any part is - do you nave a part number? Well, do you?
It took me a couple of minutes, but I have the Ford engineering part number, its assembly line replacement part number, the Ford service stock number and the Motorcraft number.
One objective of this forum is to educate its members.
I got the original Ford part number, correctly referred to as the "engineering part number" from the "1969 Mustang Electrical Assembly Manual" (AM0028 pg 10). If you haven't got a set, I strongly recommend you do. Get the paper version. You can't mark up the CD version. From there I went to "Ford Car Parts" (aka the MPC) 1975 version, available in this forum's library (courtesy of a T-Bird website) where I got the service stock number. A quick search of my favorite internet search engine, duckduckgo.com (Google records your activities and sellsd them) where I found several sources.
Try these numbers:
C9ZB-11652-B
C9ZB-11652-C
C9ZZ-11654-A
SW-817
Jim