Preserving Baseband While Downgrading to 4.3.5 from iOS 5 Beta 6

[iFlames]

My iPhone 4 was on 4.3.3 when i got it. Baseband was 4.10.01. I upgraded it to iOS 5 betas as they were released with preserving my baseband.
I couldnt unlock but now i want to downgrade to 4.3.5 (I cant downgrade to 4.3.3 as i dont have its SHSH blobs saved).
Can anybody tell me how i can preserve my baseband and still downgrade to 4.3.5 or 4.3.3 if possible.

[i.Annie]

There isn't a need to preserve the baseband. It is already not unlockable. And I believe 4.3.5 shares the same baseband as 4.3.3.

[iFlames]

Does 4.3.5 have 4.10.01 too? I wasnt sure about that. Thanks

[i.Annie]

I do believe it does

[iFlames]

Can i downgrade to 4.2.1 ?

Or can i upgrade to beta 7 while preserving my baseband and then unlock with gevey sim

[i.Annie]

You need SHSHs for downgrading to 4.2.1.

I don't believe the Gevey SIM is compatible with iOS 5, regardless of baseband version.

[iFlames]

I have SHSH blobs of 4.2.1 but i keep getting error 1

[i.Annie]

According to iPhone Wiki:

Error 1
You are attempting to downgrade an iPhone from iOS 5 to iOS 4.x. To resolve, use either custom firmware created by PwnageTool/sn0wbreeze or use notcom's FixRecovery utility available on his site.
On an iPhone 4 downgrading from iOS 5, use the option in TinyUmbrella to allow a baseband "upgrade" to bypass the error and go back to basband 4.10.1.
Unable to downgrade. Try changing the USB port (the back one of chassis is better) and restart computer.
The installed version of iTunes may also be too old. Update iTunes.

[iFlames]

It worked! Thanks a lot i.Annie.
I checked the "Upgrade iPhone 4 Baseband" on TinyUmbrella, but still got error. Then I tried fixrecovery421 by notcom and my iPhone booted just fine!
Thanks again.

[i.Annie]

Thank the iPhone wiki