What gen is your iPod? If it's an old one you can downgrade without shsh blobs. As for jb tools I suggest pwnage tool.
And I just saw that there's a semi-tethered jailbreak for ios5.
Backing up blobs with timyumbrella is a good idea whatever the case though.
If you ever want a lower firmware just download the ipsw of the version you want and shift restore in iTunes. This only applies to older devices (no blobs needed to do this)
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