I've now found mention of a 4.90 that came in the 2004 Xterra, which might also fit in our diff
New graph of just those lowest-two found so far (4.636 + 4.900), with 7th gear added since max speed limit is (finally) becoming an issue at these ratios. I have feeling there are probably other tradeoffs I'm ignoring if I push this too far, also (like time lost to the 7AT's relatively-fast shifts if I'm shifting much more often), and that aside my max speeds in 7th with those gears are ~160 and ~150. I'm not hitting 150 anywhere yet, but I probably could eventually (esp, again, with the gear change itself helping out).
