I hang around some pretty good hardware stores, and I don't
recall seeing anything near the size of that clip.
But that's just my
And in case the part # is no longer available,
some experimental alternatives might be:
-- carefully bend a finish nail
-- a cable staple from the elec. supply at H-D/Lowes.
If you need better info on either of the above,
I can snap a pic of mine (removed for some interior work)
with some examples, and include the dimensions.