Ford trucks in the 60s and 70s had a 3.54 Dana front axle and a 3.50 Ford rear axle.
But if you got the optional gears it was 4.09 (or 4.10) front Dana axle and 4.11 rear axle.
The common 4.88 gears are actually 4.89 and 4.86
4.27 gears are paired with 4.30 gears. The list goes on and on. And it isn't even consistent of the front is the higher or the lower ratio.
They don't have to match.If they had to match there would be no need for 4WD because you have enough traction. When you lack traction and need 4WD, tires slip. And a little variance in ratio is no big deal, tire slip will take care of it. And if you drive anything except a perfectly straight line (turn the steering wheel at all) the tires will slip in 4WD because the front axle is taking a longer path than the rear axle.
Anyone that says the ratios have to match has spent too much time reading text books and is too far removed from reality. Plenty of book smart engineers in the world that have no practical understanding of how things really work.