Taking the Plunge (Gear Swap)

I've towed with ratios from 3.07 to 4.56. The transmission will still pick the gear that best matches the engine's power band. On my '05 Hemi powered 2500HD Ram, I went from 3.73 to 4.56 when the carrier bearings retired at less than 100k miles. All it accomplished was the inability to shift to a tall enough overall ratio to lower rpm at highway speeds when not towing. Even around town I kept waiting for it to shift one more time. It didn't shift as much towing because it was howling like a banshee all the time instead of only when it needed to. Now that I got that question answered, I'll be sticking with 3.73 and a casual downshift on the slightest uphills. Hopefully you'll be satisfied with the results.