When under load or going uphill at between 68 mph to 75 mph on cruise control, when the speed drops by 3 mph, the engine will downshift two gears to bring it back up to cruising speed.
How long have you had this vehicle because that does not sound like a problem . Or has it just started doing that . Any chance that this is your first experience with cruise control?
Sounds like normal operation to me.
Sounds like normal operation to me, too. But I don’t know ANYthing about the truck or the hill except the year and model.
If you want better answers, add a LOT more detail, and we’ll try and help.
It’s normal for it to shift out of lockup (1 shift) then down to third (second shift) on a decent grade. Sometimes, on a slight incline, my 05 Sierra will shift out of lockup only.