I've had really good luck on engines and gear housing with Napa blue RTV sensor safe sealant. I guy it in the caulking gun size tubes. (About $10) I clean the mating surfaces so they are free of oil and old gasket material. Then I wipe the surfaces with lacquer thinner to get off the oil film. That allows the RTV to really get a grip. No leaks if put on properly. It's amazing stuff. You can save a lot of money on gaskets if you use it properly.
