oil leak at back of engine

I just replaced the rear main seal, oil pan gasket, rolled in new rods and mains, and stillhave a small oil leak at back of engine, appears to be from the drivers side. I believe it is either main seal, cap to block, (I lightly siliconed surface) or oil pan. Anyone have any ideas what to check to determine why it still leaks, or how to tell if it is pan gasket, rear main, or both?

Check the upper bell housing bolt on the drivers side, this hole is threaded right into the tappet chamber and has been known to be a source of nagging oil leaks. The oil leaches through the threads, and runs down the back side of the engine appearing to be a rear main, or pan gasket leak. It's worth a look.

Wayne (SAWDOFF) Pearce

My valve covers were leaking from the middle. That managed to run along the block and drip on the header underneath, vs dripping on the header where it bolts on.

I had a buddy with an A4460 block that had a persistent oil leak from the rear of the block. It turned out to be a machine mark on the block where the rear main cap and block mate up. He used a little red loctite between the two surfaces, torqued it down, and gave the loctite time to set up. The loctite filled the gap and solved the leaking issue.

Did you off set the seal ends so they don't match the Main cap to block parting.