I have a 3.5 ton jack and it was about 1" short for getting them under the right side as my garage floor is not even. I had to stick a piece of 2x4 between the jack and the diff to get the car high enough to get the rear to clear. I was under the car for quite a bit of time as I was installing downpipes and have never felt so safe. Not to mention it was my first first clutch install. My brother has about 700 miles on his car and it's working great.