Transmission ID?

I drove a truck that had a 9 speed. The shift pattern was 4 on the low range and 5 in the high. I don't know why that one was and no others that I have seen did not have the same shift pattern. However, when you think about it, the only reason not to use lo in the high range is redundancy, not load. A ten speed uses it, and although the ratios are different, why would that gear be a weak sister in the 9/13/18, but is ok in the 10/15? Lo on the high end is the same as 4 on the lo, but you can split it. However, that split gear is not enough gear at that speed, so why bother? If there is no need for that gear in overdrive, it makes sense to use 4 in the low range, and only start splitting from 5th.