This may seem like a silly question, but I learned to drive on stick shift and haven't had to deal with this situation until this past Thanskgiving when I was driving over some mountainous areas. On automatic transmission, is it OK to shift from Overdrive to Drive or to 2nd gear and back WHILE you are driving, without stopping or slowing down? If yes, do you have to be in certain speed range to make these shifts? I was starting to climb a steep hill on overdrive and felt the truck losing speed, but I was afraid to downshift on the fly for fear of damaging the transmission. With a stick shift like I was used to, there would be no problem because I'd push on the clutch, but it seemed really strange to just shift on auto without doing anything. I've been asking around but folks either didn't know, or thought it was OK but they hadn't done it themselves, so I still don't have an answer. We Californians are such wusses. Thanks in advance.