Steel or cast 340 crank?

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Now heres the real question;
How can you tell an oem forged 340,from an oem forged teener?

Answer; Piiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiing vs Piiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiing
Only works when they are side by side, and with a stopwatch; heehee.

Or put 'em on a weighscales