2004 Intimidator Monte Carlo SS
 

My jack slipped and the subframe fell down. The steering has a shaft with splines. I can't get the lower shaft to go back into the main shaft fitting. Does anyone have any suggestions?

Maybe you will need to get another from a salvage yard because it my be bent, or if you can jack it back up in the area of the of the bend and hopefully get it straight.
These cars don't have much of a frame so if you jack it up in the wrong spot stuff will get bent. Good Luck with your repairs.