Trailering in OD

[Genie Aye]

As stated--depends on your tow rig.

I towed boats over 40000 miles in a year with my Tahoe, boats from 20 to 27', and always left in overdrive. The computer will tell the tranny what gear it needs to be in.
PS-That is the factory trans in the Tahoe with 188,000 miles, serviced every 30,000 though.