The stitch behind the back pocket distinguishes the 66 single from the chain.
It was produced in 1973-76 for single stitch and 1976-80 for chain stitch.
However, it is often impossible to check the stitching by hand.
In such a case, judge by the fade on the front side of the back pocket.
One point!
It’s the back pocket striped fade.
It’s the same as the hem fade. A single stitch makes the striped fade weaker, while a chain stitch makes it stronger.
However, dead stock cannot be judged in this way.
We recommend that you acquire this skill and challenge yourself at a vintage shop.