oil leak

[GTOboi65]

hi i have a 1978 gmc, with a fairly modified 350. There is an oil leak at the rear of the engine block, and i can't see where it is comming from. i know it is not the oil pan, i have replaced the gasket three times, and the oil pan once. if you have any suggestions, they would be much appreciated. thanks.

[roger]

you may have a rear main seal leaking or it could be 1 of the 3 oil galley plugs in the back of the block right above the rear camshaft plug or as i recently discovered on my own 350 i found a small crack on the top of the rear of the block under the intake manifold end seal

[truckngrizzly]

yea it could be one of those plugs or it could just be the rear seal of the intake manifold.