Trying to find what driver my printer is currently using on OS X
In Safari, enter the address (without quotes) "localhost:631" to view your CUPS administration page.  The tabs along the top are fairly self explanatory.

Administration > Manage Printers > Select the printer.  This will show you the driver that it is currently set to use.

If you instead receive a message that the web interface is currently disabled you will need to first enter this line into Terminal and press return.

cupsctl WebInterface=yes