Its easy to seal the 4 corners and the flats under the hold downs.Before you install the valley pan just put a thin bead where the hold downs go on the block and I just put a small bead at the 4 corners where the tray meets the head.Install the valley pan and the hold downs and intake and you are done.My last one was on 10 years and never leaked.Only reason I redid it was I went to aluminum heads.I use antisieze on all the bolts.Never had oil migrate up them and they will always come out easy. Rocky