Texasdoc Tom before we get crazy, buy a dye kit from the auto store , clean and reassembly the motor and trans and run it. The dye leak will show you where it's coming from. This will take all the guessing out of the location and how to fix the leak. Kits about 40.00 bucks. Pour into the motor and let run or drive for 10-15 minutes. put back on stanks and check with light and glasses. Disassembly and repair. Good luck. If you find nothing than retest the trans with the same dye and test. You could even have a crack in the block and not see it or porosity. Hope not for either. Does the back of this block have allen head plugs for the
oil gallery hole and are they sealed with a sealer? More picture would help too. Rick L.