That thread is 12 yrs old and full of misinformation...I would not give it too much regard in making your decision. My understanding is that all 3/8 chain is .063 at the ties and the narrower gauges are thinner only at the portion of the drive link that runs in the bar's groove. This allows all guages to use the same nose sprocket. If I'm wrong on that then the nose sprockets have to all be .050 in order to run the narrow pitches and the .063's. Look close and you will see the step in the width of each drive link where it is narrower.
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