Scott,
We have inherited some older Cisco 7960 SCCP phones that I would like to upgrade/change to SIP and use on our OpenSER installation. The phones are on release 3.1, and the latest release on the Cisco site is 8.2.
Have a look at http://www.cisco.com/univercd/cc/td/doc/product/voice/c_ipphon/english/ipp79...
for the upgrade options. It look like you would have to upgrade to 6.3 first (to get the new boot loader) then to 8.2
Unfortunately, I have not been able to find the older binaries anywhere.
Have you tried to ask Cisco? You should be able to download them from CCO if you have a valid software agreement. You should even be able to download 8.4.
Stéphane