I phone 4 16 gig's with the 4.3.5 mod

[Coleus]

well i have the same problem with the same OS and baseband, try to downgrade but keep failing :-(. you can jailbreak the 4.3.5 but it is tethered. Here is instruction
http://www.redmondpie.com/jailbreak-...w-to-tutorial/

Good luck