The gaskests are hanging into the cylinders .037 enough that the fire ring on the one head is not being sandwiched between the head and the block. I just got off the phone with AFR they are sending me a set of 1021 Fel pro head gaskets back with my heads. I asked them to dumb it up for me and mark the heads and gaskets drivers side and passenger side (even though it shouldn't make any difference as long as you have the front of the head gasket towards the front of the block).