Is the client OS windows based? If it is then I don't think you will be able to use tar to extract any of the files because:
1. The procedure for image recovery with tar detailed in the NetBackup System Administrator's Guide for UNIX is not valid and does not work for backup images of Windows clients.
2. The procedure for image recovery with tar detailed in the NetBackup System Administrator's Guide for UNIX is further limited to a backup image of 2 GB or less.
BUT,
If the client was UNIX then perhaps you could import the tape onto a temporary UNIX server and then use the procedure for image recovery with tar. I don't know if that would work either, but if I had the resources, then I would give that a try.