I used bricks. My LS1 Trans Am was so low that th brick wouldn't fit so what i had to do was cut a brick in half length wise, squeeze it between the wheel and wheel well, then back onto that. Once the car was on the little half brick, I would put another two bricks next to it, and one in the middle of them like a pyramid. Then back onto that. At this point i had the ground clearance as well as the 2 bricks' worth of clearance and it was great! Or you can go to sears and buy a specific car jack for lowered cars, you only need 1/2" of clearence, but at $129.99 compared to my GM jack for $19.99 that hant failed me yet in 6 years, i'll just keep backing over bricks. Only takes a few minutes and they only cost $0.44 each.
Red Bricks- $0.44 each,.....
GM performance jack- $19.99......
Having to cut a brick in half to back onto, in order to back onto more bricks, just to be able to jack up your bad *** Trans Am.....priceless. lol