340 rear main choices- race motor

I had a leaking rear main seal that I attempted to fix 4 times with no success until I did this.

I found that magnum small block engines have a slightly smaller crankshaft rear main seal diameter making the magnum rear main seal clamp tighter on a non-magnum crank.

Also, the magnum seal is the orange material which remains more pliable over time.

This is what I did to finally fix this irritating leak 5 years ago with not a drop since.