There's a guy selling them on eBay - he bought out all of the NOS of the OEM for a bunch of auto manufacturers, and he has them.
His eBay auction name is acme-antenna
He's in Georgia, as I recall, and he's a great guy.
If he's not got what you need listed, send him an e-mail at:
stan7284@bellsouth.net
Incidentally - I got the one with the spring-loaded base, like the one that came with the 65 my grandfather bought factory new. I prefer it because it gives when something whacks it, rather than bend like the straight ones.
Hope this helps!