Need help identifying this 1275/1300 crank

[Exminiman]

Are you sure those “cracks” are not just on the surface ?

[Gary Schulz]

I am thinking they might be. The mag inspection place I use doesn't provide a lot of details on depth though they also do X-ray inspection as well. I may just have one of them re-ground to see what it looks like afterward.

[Exminiman]

I am out of my depth here! but could the cracks just be features of the nitriding layer?

There is another thread going re original cranks which suggests that nitriding layer may of been quite thick on S Cranks....