Customer hard drive failed so I swapped Fiery's with known good one. Could ping and web into but could not print. Did not realize at time the Fiery software version is 1.1 and print driver is 2.0.. Without upgrading system software can I use earlier print drivers to resolve printing?

You can download the drivers from the Fiery using the Fiery Web Tools, that way the driver version and the Fiery system version is matching.
If you have the system software ver 2.0, it's better to upgrade the Fiery rather then to downgrade the printer driver.