You need to tell me the printer models. Mac printer drivers aren't as straightforward as Windows drivers. For many non-postscript printers, the manufacturers have created USB-only or Bonjour-only drivers. Apple calls these drivers "monolithic" drivers because they bypass the multiple connection protocols supported by CUPS.

Gutenprint drivers are open-source drivers included in OS X (and in linux, too).
You can update Gutenprint from:
Gutenprint for Mac OS X