You dont have to change the axels if you have an sr20 already in it.. Thats if you start with Ga16...Because the sr20de and he ga16de do not have the same tranny... The sr20 doesnt have a good tranny.. It is only good for 300hp. Then it tends to break the second and third gears.. Cryogentics and shotpennig helps.. The bluebird trans. is also a little stonger,but has to be customized to work.. Make sure you get a tranny out of a FWD bluebird ,if you take that route..