We have a problem with the Dodge race truck we are building. It leaks oil AFTER it runs for a little while. We saw oil dripping from the bell housing so thought it might be a rear main seal. But once we cleaned of the bellhousing and flywheel we discovered the oil was seaping down the block from above. So now I'm thinking it can really only be a head gasket, valve cover, or PCV system. Remember that it doesn't leak under pressure (when the engine is running). I know I'm probably missing something but we can't figure out what it is. Its only on one side of the block which has one freeze plug halfway up, and then the head and valve cover.