Greetings All, RockBit is correct. If memory serves me, all 427 FE blocks casted before 1965 we all top oilers. The reason for the sideoiling conversion was to protect the engines from
oil starvation during racing and hard cornering paticularly NASCAR racing. If your block has pressed-in freeze plugs, most likely it was casted before '65 and a top oiler. You should be able to find the casting date code on the block where the
oil pan bolts to the block (sorry, can't remember exact location) My 427FE has freeze plugs and casted in November 1963, therefore a top oiler Also, the Ford FE Forum is a wealth of information and can decipher all casting markings for you.