Like these: http://www.steeda.com/steeda-s550-mustang-ultra-lite-chassis-jacking-rails-15-16-all-555-5205/ ?I made one of those from a block of aluminum the day after I brought my Shelby home, cost me 15 minutes of work. Then after the first session lifting the car, I decided jacking rails were the way to go.
10x better with the jacking rails.