It may be worth noting that 3.46 x .8 (5th) = 2.77
That is taller than the 2.88 (4th 1:1) that was used with some 3L diesels.

Yes, 1st with the 3.46 is short (3.9 x 3.46 = 13.49), however, as we can see, without changing the gearbox internal ratios, making 1st taller also shifts 5th upward too far. A 3.07 x 3.9 = 11.97, and 3.07 x .8 = 2.46

The gearing as delivered in Europe (3.46) w/5-speed is just fine for a cruise south thru Bavaria, and then a week spent crawling around in the Austrian/Swiss Alps!