A sure fix would be to use aluminum plugs in the aluminum block with liquid teflon. Same expansion rates with heat build-up. The steel plugs contract and expand at different rates, causing some of the oil seepage problems in aluminum blocks. O-rings help, and are supplied by Dart for their aluminum blocks, and Shelby sent a set with my block. Hope the leakage is simple to fix after all the work and time involved. Joe-JDC