I've been working with several of these cars, and have noticed that a small clip for the anti-spin differential have broken into pieces, and caused noise frome the rear axle.

This clip ain't available from MOPAR as a part, and you have to change the entire differential to get new ones.

Does anyone know a place to get hold of only the clips?

If the clip was available, you could just clean up the differential and mount the new clips.

Although I don't know the clip of which you speak, certainly there is SOME manufacturer that has the part available. Just because MOPAR doesn't carry it doesn't make it not available elsewhere. I'd check at transmission and axle repair shops, specialty racing shops, and with the manufacturer of the axle itself.