Your main bearing is definitely danaged and it should be replaced. The material has failed. It almost looks like it ran short of oil at some time for a few seconds. Also there appears to be a lot of sludge in the motor. It looks like it has been run on non detergent oil and maybe a long time without a change.

Take your time with the seal. I like to use a pair of wire cutters and splt the lip. Then I peel it right out.

I would drop some of the other caps and have a look at the bearings. Maybe the rear main suffered a blockage. It wouldn't hurt to look at the rod bearings too.Your crankshaft looks pretty good to me.

1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed

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