I have 2 sets of what are supposed to be AAR heads. Both are casting number 3418915 and both have the "360" marking. Both have the offset rocker assemblies and offset intake pushrod holes. One set has the "J" or "U" casting by the spark plug holes and the other has a "Z" on one head and an "O" on the other. Galen's book says that the "J" or "U" heads are correct. The "J/U" heads definately have the bigger intake valves. The "Z/O" heads are on the car so I can't tell. The offset pushrod holes and rocker assemblies on the Z/O heads have me stumped. Could they be correct? I have pictures if it would be helpful.