Why not a 2 speed or quick change rear end option

The advantage of a 2 speed or quick change rear end is that when you are towing you could pick a rear ratio that gives you 6 useable towing gears instead of 4-5. It would also give you more available power at most road speeds.

When not towing you would be back to a ratio that gives you good fuel economy and lowers rpm for empty driving.

The gear vendors stuff is nice and also expensive.

But with the coming 9 and 10 speed transmissions soon we will have most of these advantages.