lol, no it does not now, nor has it ever, had a 1µ absolute rating. Gotta love marketing... I find it funny that the Cat filters are still the filter of choice with the aftermarket filter kits when the Cat 1R-0750 hasn't been the best fuel filter in 20 years and the f/w sep was never as good as the Fleetguard/Baldwin/Donaldson filters. It goes to show that hype sells, not facts. For many years the aftermarket filter setups had far worse filtration than OEM, now it's hit and miss.
The 1R-0750 was rated 2µ absolute on old test standards. The standards were modernized in 2004 and the 1R-0750 is rated at 4µ absolute. The P551313 and DBF5814 are 3µ absolute, with the DBF5814 having much better media which is why it's the preferred filter.