Well, you have to be more specific than that. What year is your V6 Mustang? Some years are much easier than others. Also, what V8 do you want, you can choose from 5.0's and 4.6 mod motors. I just put a 5.0 in my 99 V6 Mustang and I love it! I did a write up with lots of pics and steps along the way, you should check it out!