is this a new iPhone 3GS model?
That 3GS is from week 44. iPhones produced after week 40 2009 have the new bootrom if that is what you are referring to by new model.
i tried all methods and no success to jailbreak !!!
Have you tried blackra1n? What version does the USB controller say the installed bootrom iBoot is when you connect it in DFU mode?
The roughly week 40 message was intended to help people who wanted to be able to get an idea of the bootrom status without opening the box or turning the iPhone on.