Derek,
I know the clip you are looking for. That is why I suggested picking out the S-style cage nut close to the size you need & remove the nut and adjust the openings to fit your vents.
You can contact Advance Components, (972)446-5500. They have the clip in the photo. They may have the size you need.

Harold
Attachments
S-Clip Advance Components.jpg (22.22 KB, 95 downloads)

Last edited by Harold46; 11/02/2019 4:07 AM.

Harold
Is a restoration ever finished?