Is the iPod Touch 3G 32GB able to downgrade from 4.0 to 3.1.2?

[Grapesipod]

I keep reading posts of people saying this is possible. I had originally, when I bought my iPod Touch 3G, firmware 3.1.3 and jailbroken. However, when I updated a Cydia app (Activator to 1.4), it ****ed up my iPod and I had to restore. So is it possible to revert to 3.1.2 without using SHSH blobs via Shift+Click Restore?

[Poseidon79]

You MUST have your SHSH blobs on file with Cydia in order to downgrade.

Caching Apple's Signature Server - Jay Freeman (saurik)