It has a 35 inch height limit on it. It used to have no limit on it at all. My friend's son rode it when he was 9 months old. Sometime between when he rode it, and when my daughter was born, they changed it to having an age limit of 3 years old. In 2000 they replaced the tracks and when they opened it up for the summer they changed that and gadgets go coaster from an age limit of 3 to a height limit of 35 inches. When we noticed the sign we decided to see how close she was to the limit. Since we had her measured a month before at the dr and she was about 32 inches we never thought she would actually make it on the ride. We walked up and the CM said you're fine. So we got in line, back up the where the line splits in two and she was measured again, still okay. Get to the end of the line and measured again, still okay. Get on the ride and the CM in the booth called down and asked her to be measured again. They had to stop the car so she could get up and stand so they could measure her. He gave his agreement, she got on and rode the ride, and has been riding it ever since.
At age 3 1/2 she rode every ride that had a height limit of 42 inches or lower. At age 7 she has been on everything except maliboomer. She has not been on Tower of Terror at DL, but she did ride it in WDW when she was 3 (she insisted on riding it and while she doesn't want to ride again, she was fine on the ride).