[L88]

I've got the Corvette by the numbers book. And in the engine block section they talk about 3 exterior holes above the oil filter boss. There saying that the 2 bolt main blocks front hole is 5/16", the center hole is drilled and tapped with 3/8" pipe thread, and the rear hole is 1/2" coarse thread. On a 4 bolt main block the front hole is 3/8" pipe thread, the center is 1/2" pipe thread, and the rear is 1/2" coarse thread. Thats what I meant when I said I had the bigger holes.