First off i don't think you want air cylinders. They ride like [censored]. You are going to want air struts. I am looking for some myself and i found them at aim. Here is the link
Ford contour struts . They are about 1500 for a complete set with a crapy compressor. If you drive alot you should upgrade your air compressor to something more heavy duty. They have kits but you still have to buy the size of air line and valves and so on seperate. Like i said a total package is about 1500 but you still need that new compressor. At least i recomend it. When are you thinking about buying them. I guess they take stock contour struts and modify a air bag bracket for the bag to sit on. I would recomend a rear sway bar to help keep good handling. I hope i helped.
