Restore UNIX dump

I need to restore a Digital Unix 4.0b dump of 5 system partition file systems. I do not know the dump command that was used to dump data to the tape, only that it was the Unix dump command. This was done 12/29/99. There is data there that needs to be restored. 6 tapes were used to dump all of the data to tape. However, when I try to run the restore utility, I can only get to the middle of tape 3.

Does anyone know of a way to read a Unix dump tape other than the restore command or how can I use the restore command to get the data off of the tapes?