TH475 is the same as a TH400 externally. Most of them had a drum emergency brake on the tail shaft as they were used in motor homes, C50 or bigger trucks, and busses. Might run into drive shaft issues if the drum brake is present. Internally they are different. They have strait cut gears instead of angled or sun cut. They are much stronger. They tend to have a whine noise when running down the road because of the strait gears.