I am going to look at a pair of 9 thread cylinder heads, the seller thinks they are from a 2004 cobra, are there casting# or build date's to verify what they are? they have valvetrain and cam's, what is the difference between the 2003-4 cobra and mach 1 besides cam profile? thank's for any help i just do not want to buy head's and find out they are older cobra or lincoln heads.