I consistently leak a small sheen of oil at the top back of the engine. I just replaced the gasket on the intake manifold, and torqued in sequence. Didn't make a darn bit of difference. I swear I even feel a small gap (~.04 inches) at the back of the block between the engine block and the manifold.

I have a 1989 Big Block 454, from the Tonawanda Performance Parts Guys, I think. Some Block Numbers I can see:
Driver Side Rear- 14015445
Pass Side Rear- F089
Front Center top- TMOXAA

I have an aluminum Intake manifold with casting number: 3933163
I believe this is for a '69 396 or 427 engine. It runs fine with the cowl induction and a 2003 holley street avenger 770 carb.

All my books say that Intake 3963569 is correct, which is not what I have.

Do I need to find a new intake to fix my oil leak? There is not a doubt in my mind it is coming from the back of the engine at the sealing edge between the block and the intake. Fluorecent dye run in the oil visibly shows the same effect.

If your still using rubber or cork gaskets at the ends throw them out and use gm 88861417 engin sealer.Run a 1/4 in bead and tighten the intake as normal and let dry.Use 3m spray adhesive to hold the runner gaskets in place also.