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The bearing is still on the crank. Just noticed that.

Sorry forgot I had read that.

2 radiators #s that i would like to know what they were in first one is 18398---3443977 and the 2nd is 38086---3574636 and help would be nice both are out of a bodys as far as i know one is a 72 demon rad im sure

You may never find the root cause but sure looks like oil starvation to #4 rod,dosent look like the bearing had spun before seizing on the crank,lot of heat there causing the rod to break ?

Were the rods checked for roundness after the rod bolts were replaced? Were the rod bearings check with plastiguage for clearance when it was rebuilt? The appearance of the bearings sure don't match up with what the crank looks like. With the center of the bearing pounded out, I suspect the clearance was a little loose to begin with and the 45K miles finally caught up with it.

I guess that's where I dropped the ball, no none of that was checked. My thinking was I checked rod bearing clearance once not long before it was rebuilt with plastiguage, and it checked within new limits, so...... I know what you mean, the crank looks good, and the bearings bad, seems like both would look bad.