For the Rolex 8171, the general perception is that the Steel 8171 should be a Precision watch while the gold or half gold Rolex 8171 should be with "Officially certified chronometer".
However, from my recent find, I realized that it all depends on the movements. My steel Rolex 8171 movement has engraved 17 Jewels Rolex Geneva and was timed to 7 positions while the movement of some version has the engraved Precision.
I hope I should to find more pictures to see the differences... Cheers