I recently visited my local suplus store and found they had 20-30 Rockwell R65C21P PIA's for sale. These look like new old stock. I bought two for $3.50 each (plus 7.75% sales tax). The date codes were 8415 and 8437. The other # was 11449-11 (I'm not sure what that's for, my guess is a die identifier or factory ID). They appear to be 1MHZ parts.

If anyone is in need of some of these, contact me via email or PM and I can get some shipped to you.

Daryl