[Christ]

Also worth noting... any gear reduction device is also a gear increasing device in reverse, for the most part. A small transfer case reversed might do exactly what you're asking for and provide an option to have two ranges by shifting from 2wd option to 4wd option.

I've often used 4L on my F150 (gone *sniff*) while the front hubs were unlocked to get a "crawling" gear for different reasons.

Imagine for a second that 4L gave me an drive speed of 1:0.5. Reversing the transfer case then, would have given me a 4L drive speed 150% greater than my input speed, or a drive ratio of .5:1 between the transmission output and the axle gears.