ok so i recently bought a fe motor and was told it is a 390. so everthing ive read in books and online don't answer my question. the block is ribbed on drive and pass side. looks like the ribbing on a 406 or 427. also has what looks like cross bolt holes on one side only. there is no casting # that i can see and no A or C scratched or cast into the back of the block. the oil galleries are drilled so i do know its not a hipo. did ford make another motors with ribbing. oh the heads are for 390-428