My 01 Silverado, auto, OD. may need an adjustment somewhere, but I think it's a programming issue. Anyway, it goes into OD too soon and doesn't downshift for hills so I'll do it manually. Part of the issue might also be the nut behind the wheel. The computer decides to downshift based partly on how much pedal is applied, and if I don't increase pedal on the uphill then the computer doesn't know it's on the uphill.
As for going into OD too soon, and this is just my viewpoint, I don't think it has any business in OD under 55 unless I'm going down hill.

A computer is only as good as its program.