I had the same problem, could find them but only in a set for an E body, had a bunch of others I didn't have a use for. I found these from Restoration specialties, 2.5in. center dist. They're in their catalog but not all from the catalog is on the website. You'd have to call them, $1 / ea.
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That is what I ended up using. They are not 100% correct, but look similar and hold the wires in place.
Below is what I need to use to be 100% correct, but in black.