Foreign Currency Bank drafts are valid for 6 months. You can get it easily from SBI or ICICI.
Only INR cheques/drafts are valid for 3 months. There is already a thread of discussions about the same.
Get your bank draft from ICICI Bank, theirs are valid for 6 months. Foreign currency bank drafts issued from India are generally valid for 6 months unless and until mentioned otherwise. I got mine from ICICI Bank.