No you do not have to pull the engine and I gree with this.Plus the gear ratio has be the same or the transmission will not work.If you get one with a differant gear ratio differant,change the final drive and sometimes the wiring inside the transmission.Look at the color of the round plug,it will be black or grey.To find out the gear ratio is,there is a metal tag on the back of the transmission near the final drive housing such as AF,WS,etc in big letters.There are another set of letter vertically and look for the AF,WS,etc and ther should be another letter after that.That tells what the gear ratio of the transmission is.