While under the Commodore repairing the exhaust system, I had a new U bend made up and I then welded up the entire 2.5'' piping to form one piece. I noticed a small drip on the transmission drain plug and after further investigation I see on the rear right side of the block oil build up. Block fittings wise I can't see anything that would be causing the leak and am now thinking with the help of the forum the cause might be the tappet cover seals which were last replaced 220,000 ks ago so I'm to degrease the entire block and gave it a water blasting using a short hand piece and am going to replace the right side seal and see if that stops the oil leak. The example engine in the picture is of a 100,000 k engine that's going in our Austin project. Wondering if anyone else has had an oil leak in this area and was the seals the cause.