Jeff, I don't know that Ford has offered a 4.30 factory gear as a production option on trucks...we've beeen solidly into the CAFE standard and emissions-**** years since Ford intro'd the 8.8 axle.
I know that SVO Motorsport 4.30-ratio ring and pinion set P/N M-4209-G-430 is available for the 8.8, but the lowest I've seen as a production option in trucks is a 4.10. Perhaps the 4.30 was used in the Mustang Cobra "R" model of a couple of years ago. The 4.30 might also have been factory-supplied as a tuner base to the Saleens and Stillens of the world. Another possibility would be a rare towing package on an 8.8-equipped Ranger. Let me know what you find out; interesting question.
Ed