Shift! **** You Shift!

I've been towing for years with GM's ubiquitous 5.3L coupled via the old wide ratio 4-speed transmission to a 3.42 axle ratio, a combination which forced me to always tow in 3rd because the spread between 3rd and Drive was just too great. I recently upgraded to a '12 Silverado with a somewhat more powerful 5.3L, also with a 3.42 axle ratio, but coupled via the newer narrow ratio 6-speed. Before my first tow I was sure I'd be towing in Manual 5 but it turns out that transmission is much smarter than I am and if I just leave it in Drive it always remains in 5th at highway speeds, never goes to 6th, and downshifts appropriately to 4th or even 3th as road conditions may occasionally call for. Couldn't be simpler. :B