Hello, It has been my experience that the 1956 - 1959 Cessna 172 straight tails (especially the 57 model) take less ground roll (as much as 400 feet) than the early 60's models when they first introduced the swept tail. All have the 0300 engines. Other than the swept tail the main difference is that in 1958 the landing gear was moved aft by three inches. Any one else experience this or is it just the particular planes that I happen to fly. Engine time has been about the same on each plane.