The oil tube boss in my G's engine is cracked with about 1/3rd of it missing. If the other piece comes loose it will constitute about 1/2 of the total diameter. My best idea would be to mill the boss below the broken area, extend the threads, and add changed length to the tube. I doubt this is a unique problem so would like suggestions for easier or better repair.
Significant work has been performed on the block so not ready to throw it away.
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Marshall Larson