Hi Ted, we had one of the non powered Thomas engines. It was hollow inside except a smoke generator and had a Honda generator to provide A/C electricity to run it. Our HIT entertainment rep told me there were 6 standard gauge, and the 3 and 2 foot versions that you mentioned. It might be fun to see a Thomas triple header wouldn't it? The little kids thought Thomas was pulling the train and gave no thought to the big diesel that was on the other end. Great event though, we had 34,000 guests in five days!