My buffalo NAS has died, but I think the hard drives (in raid 5) are OK. Can I just put these hard drives into a new buffalo NAS ( same model, LS-QVL ) and get the raid back on and retrive my data?
That may work. To be safe I would first make an image of each RAID member drive.
The other option is RAID recovery software like R-Studio/UFSexplorer/GetDataBack.
Or if you need help I do a lot of remote RAID recovery work and have seen the Buffalo LinkStation LS-QVL in the past. I can tell you each RAID member drive is divided into 6 partitions with partition 6 being the data partition. The LinkStation operates using Linux Software RAID aka mdadm and your data volume is in Linux XFS format.