The body was an mbx5 body the crowd pleazer version. Basically what I had to do was trim a little more off the front where the steering comes through the body. The front body mount hole was drilled a little infront of the factory marked one. The hole for the engine head to come through was cut a little further back then what was outlined from the factory. Also when cutting the body out at the bottom. Try and leave as much matterial at the back as possible. I also had to flip the rear boddy mount upside down. This allowed the back of the body to cover the whole chassie. All I do is put the back of the body on first and then pull it down over the front. I don't even have to use a pin on the back being as how it is puside down. It is kindof hard to explain. but the body looks awsome and didn't take alot of work. The jp-1 made a huge diff in my .26. I don't know if it will help the .21 as much or not but I imagine it would. Also just by switching to O'donnel fuel I was able to lean the engine out 1.5 turns and it still runs about 20 or 30 degrees cooler. I was running trinity 30% before now I am running O'donnel 20%.